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THE EXPANSE OF HEAVEN. 



THE 



EXPANSE OF HEAVEN 



6) 



A SEEIES OF ESSAYS 



WONDEES OF THE FIRMAMENT. 



E^A.^ PROCTOR, B.A, 

AUTHOR OP "OTHER WORLDS THAN OURS," "THE MOON," "LIGHT SCIENCE FOR LEISURE 

HOURS," ETC. 



"Let there be lights 
High in th' expanse of heaven, to divide 
The day from night." 



NEW YOEK: 
D. APPLETON AID COMPANY, 

549 AND 551 BROADWAY. 

1874, 






&z><& 



By Transfer 
JUN 6 190? 



CONTENTS. 



PAGH 

A Dream that was not all a Dream .... 1 
The Sun 11 

The Queen of Night . .20 

The Evening Star . . 47 

The Ruddy Planet 56 

Life in the Ruddy Planet 66 

The Prince of Planets. . . . . . .75 

Jupiter's Family of Moons ...... 85 

The Ring-Girdled Planet 94 

Newton and the Law of the Universe . . . .104 

The Discovery of Two Giant Planets . . . .114 

The Lost Comet . . . . . . . . 124 

Visitants from the Star Depths ♦ ♦ , 133 

Whence Come the Comets ? 142 



iv Contents. 

PAGB 

The Comet Families of the Giant Planets . . . 152 
The Earth's Journey through Showers. . . .162 

How the Planets Grew 173 

Our Daily Light . . .193 

The Flight of Light 202 

A Cluster of Suns 211 

Worlds Ruled by Coloured Suns 220 

Worlds Lit by Coloured Suns ..... 229 

The King of Suns . . . . . . . . 238 

Four Orders of Suns . . . . . . 247 

The Depths of Space . . . . . . .256 

Charting the Star Depths . . . . . .266 

The Star Depths Astir with Life . . . 276 
The Drifting Stars . . . • • • . 286 
The Milky Way . ■ . 297 




THE 

EXPANSE of HEAVEN. 



A DREAM THAT WAS NOT ALL A DREAM. 

Behold even to the moon, and it shineth not ; yea, the stars are not 
pure in His sight. How much less man, that is a worm ? and the son 
of man, which is a worm ? — Job xxv. 5, 6. 

On a time I dreamed, and my dream was on this wise. 

In a vast black space there appeared a glowing orb 
about three yards in diameter, as it seemed to me ; but 
it was nearly a quarter of a mile away from me, and its 
real nature I could not perceive. It shone with a mighty 
light, whiter than the driven snow, and more intense than 
the light from the heart of the fiercest furnace. 

Close by me I perceived a tiny globe, about an inch in 
diameter, travelling slowly along, and turning round and 
round as it travelled. Amidst the intense darkness which 
prevailed, this globe would have been wholly lost but for 
the glowing orb I have just spoken of, which lit up one- 



2 The Expanse of Heaven. 

half of the surface of the small body. Looking closer, I 
perceived a yet smaller body, little more than a quarter of 
an inch in diameter, which seemed to be moving round 
the other at a distance of about 2\ feet. 

But as I looked, wondering what these small bodies 
might be, a power of keener vision was given to me, and 
I saw many animalcules, inconceivably minute, upon the 
surface of the lalyer of the two small globes. I could perceive 
that the greater part of the surface of this globe was covered 
with a film or moisture, and in this film were myriads of 
living creatures, moving about according to their several 
powers, some pursuing others, some pursued, but for the 
most part intent in seeking what they might devour. 
Over the dry part of this tiny globe, which I could have 
held (so it seemed in my dream) between my finger and 
thumb, were other creatures in countless myriads, though 
not in all parts equally numerous. 

But what astonished me mightily was to perceive 
among the creatures moving over this little globe certain 
beings, not larger than the rest, nor remarkable in any 
respect save in this, that they appeared to act as though 
they possessed powers of reasoning. I could see that 
they constructed microscopic dwellings for themselves, 
and formed roads over their tiny domain, and made other 
constructions intended apparently for the convenience of 
their race. They even ventured, in minute floats, upon 
the film of moisture, which they crossed and recrossed in 
the most venture someway, considering that, film though 



A Dream that was not all a Dream. 3 

it was, it was many times deeper than the largest of the 
floats in which these strange creatures crossed it. Indeed, 
sometimes when the film was agitated as by some one 
breathing on it, these floats upset, and many of the tiny 
creatures upon them were drowned. At some places I 
could perceive threads, infinitely finer than the threads of a 
spider's web, laid down under the film of moisture, and 
in many places such threads were extended over the dry 
part of this one-inch globe. The object of this arrange- 
ment I could not at first understand, but I learned pre- 
sently that these creatures used the threads as a means of 
conveying messages to each other ! 

But I have no space to tell of all that I could perceive 
or that went on in this small globe. I must speak only 
of certain matters which struck me as chiefly interesting. 

These little creatures, so small that the most powerful 
microscope yet made by man would altogether have failed 
to show them, were actually able to learn a great deal about 
objects outside their tiny abode. They could not only see 
the great glowing body which as I have said lay nearly a 
quarter of a mile from them, but they had found out how 
large it was, how far away from them, how bright, how 
hot, and even how heavy. This in creatures so utterly 
insignificant, as it seemed to me — so weak and small that 
with a touch of my little finger I could have destroyed 
many millions of them — appeared very wonderful. They 
were quite unable to leave their tiny world. It did not 
even give them a fixed stand-point, for it moved slowly 



4 The Expanse of Heaven. 

onwards, as I have said, turning round and round, so that 
for half the time the shining globe was not even in sight. 
Yet these little beings had measured and weighed and 
tested it with results surprisingly accurate. They had 
found out, what I could not perceive from where I was 
placed, that this great globe, fully three yards in diameter, 
was in its way a sort of furnace, the flames on its surface 
being sometimes a foot high and sometimes even two 
feet. Its whole surface, they had found, was in a state of 
wonderful disturbance, being, on a small scale, like a sea 
of fire, and covered all over with intensely hot vapour 
extending to a height of nearly half an inch. But, even 
more wonderful to tell, these tiny creatures had found out 
what was burning (or at least glowing) in that large body. 
They had also learned the very rate at which the flames I 
have spoken of rose up above the surface of the glowing 
orb, or spread themselves over it. 

This seemed to me so wonderful that I left the little 
globe to pursue its course, and went to the large bright 
body. It was not quite a quarter of a mile away, I found ; 
but (precisely as these small creatures had somehow 
learned) about 320 yards from the small globe. When I 
got to a certain distance from it, I found the heat so 
great that I did not care to approach it more nearly. It 
was surrounded on all sides by glowing matter, not nearly 
so bright or so hot as its own substance, but still shining 
very resplendently. I found that the little beings on the 
small globe I had lately left were quite right in their 



A Dream that was not all a Dream. 5 

general surmises about this large body. I could see the 
flames they had disco vered, and could watch for myself 
many of the processes they had recognised by means of 
ingenious devices on a less than microscopic scale. The 
great glowing orb, though nine feet in diameter, was 
turning steadily round — a fact which my minute friends 
had known a long time before. Or rather I should say 
that the minute race of beings had known the fact for a 
long time, since the existence of these creatures was quite 
ephemeral, and even as my dream proceeded, though it 
appeared only to last a few days, many of these reasoning 
but ' to any thick sight invisible ' creatures had been 
born, lived out their lives, and died. 

Then I looked round on the dark space which sur- 
rounded me on all sides. I could perceive, but only as 
two points of light, the small globe on which were the 
little creatures so wonderful in understanding, and the 
smaller body which moved round it. But I could see also 
other small bodies. Not very far from me was one which 
was very brightly illuminated by the large glowing body. 
It was much smaller than the globe I had first seen, 
though larger than its companion. It was moving more 
quickly, and I could perceive that it was moving round 
the bright body at a distance of rather more than a 
hundred yards. Nearly twice as far away from the flaming 
central body I saw another globe, about one inch in 
diameter like the first, though from my present central 
position it looked larger and very much brighter. And 



6 The Expanse of Heaven. 

at a distance, about half as great again as that of the 
small globe first seen, I saw a body rather more than half 
an inch in diameter, and of a somewhat ruddy colour. I 
paid a visit to this small body, which was travelling, I 
found, at a distance of about five hundred yards from the 
great glowing body. It was a pretty little object, with 
greenish markings between the red parts which gave this 
body its ruddy aspect. 

I could now see that, yet farther away — in fact, more 
than half a mile from the bright central body — there were 
many very small objects, little more than grains of powder 
they seemed to me, travelling in a sort of ring around the 
glowing body I had left. 

My dream was not yet over, however. For I presently 
perceived yet other bodies, travelling at greater distances. 
About a mile from the central body was a globe much 
larger than any I had yet seen, except of course the fire- 
globe three yards in diameter which seemed set as a sort 
of ruler over these small orbs. The body now seen was 
fully ten inches in diameter. It was beautifully coloured, 
being striped with red and yellow and purple and brown 
belts, which seemed to me to owe their regularity of 
arrangement to the rapid turning of this body. It will 
seem surprising, if anything in a dream can be surprising, 
that although this globe was ten inches in diameter while 
the globe first examined was but one inch in diameter, yet 
the larger globe was turning round much more quickly, 
making, in fact, five complete turns while the smaller 



A Dream that was not all a Dream. 7 

made but two, for I tried both with a stop watch, and am 
therefore able to speak positively. 

A singular circumstance about this large globe was 
that around it there were moving four little bodies, the 
largest being only about a third of an inch in diameter. 
These moved at distances of 2J feet, 4J feet, 7 feet, and 
12 \ feet from the ten-inch globe on which they seemed to 
attend. These little bodies, though no larger than peas, 
formed to my judgment a pretty little scheme, their 
motions in particular being singularly regular and very 
nicely adjusted. 

But nearly twice as far away from that great glowing 
orb three feet in diameter, which I now began to regard 
as far the largest body I was likely to see, I found a most 
remarkable system. There was a globe about 8 J inches 
in diameter, and striped with belts much like the larger 
one I had just left, only it was of a more sombre tint on 
the whole. Around this globe there was a set of flat rings 
not touching the globe anywhere, though in some unseen 
way they were so associated with it as to accompany it 
unceasingly. These rings, regarded as a single system, 
had a span of upwards of twenty inches, and a breadth of 
nearly four inches. But there were several of them, 
unequally bright, and on a closer survey I could perceive 
that they were made up of a multitude of tiny grains each 
pursuing its own career as if journeying around the globe 
which was within the ring. 

Even this, however, was not all. For this globe, 



8 The Expanse of Heaven. 

besides this curious little system of rings, had, like the 
globe before visited, a family of small bodies travelling 
round it at different distances. There were no less than 
eight of these tiny orbs. I noted that the sixth in order 
of distance outwards was nearly half an inch in diameter, 
and travelled at a distance of about 8 \ feet. The outer- 
most of all, though not nearly so large— in fact, little more 
than a quarter of an inch in diameter— -was distinguished 
by the wide span of its circular path, which lay at a distance 
of more than twenty-four feet from the centre of the ringed 
globe ! 

I was now about two miles from the great glowing 
mass, which looked very small because of its great distance. 
I could perceive, however, that farther away— some four 
miles from the glowing orb — there was another of the 
small globes, and though I did not visit it, my increased 
powers of vision enabled me to perceive that it was about 
four inches in diameter, and had four small bodies 
travelling round it. Yet farther away, some six miles 
from the central fire-globe, there was another orb of about 
the same size as the one just mentioned, and having only 
one small body attending upon it, or at least only one such 
body that I could perceive. 

I now returned in my dream to the small body which 
I had first seen, and found the tiny reasoning creatures 
which I had watched before still continuing busily at work, 
collecting food, building houses, making roads, undertaking 
voyages, and — alas, poor little creatures! — quarrelling 



A Dream that zvas not all a Dream. g 

among themselves, and engaging in combats l>y which 
thousands of their number were destroyed. I found that 
many of the matters I had ascertained during my journey- 
ing were quite as well known to the more studious of 
those beings as to myself. \w this power of learning facts 
about objects so far away from them the tiny creatures 
seemed to me to be very wonderfully gifted. I was, 
however, rather surprised .to find that some among them 
prided themselves as much on these powers as though in 
some way they had acquired them by their own exertions 
or goodness. To note the ways of some of these creal ares 
— which to^ny vision seemed so insignificant and in fact 
contemptible, while they were manifestly very weak and 
short-lived — one would have supposed they had been 
mighty enough to construct not only their own little 
abodes, but the great nine-feet fire-globe which stood at 
the centre of the whole scheme of globes 1 had visited, as 
well as all these globes and the systems attending upon 
them. I was preparing to rebuke their folly, proposing 
in my dream to show them how wretchedly small and 
weak tliey were, and how little reason they had to pride 
themselves even on their certainly wonderful knowledge, 
since the more they learned the more clearly they ought 
to recognise their own insignificance: I was about, I say, 
to enter upon much wise discourse on this subject and 
'kindred matters — not foiling, in particular, to show them 
how very much stronger and greater I was than they — 
when to my annoyance and disgust I found all my dimen- 



i o The Expanse of Heaven. 

sions rapidly becoming reduced, till I was no larger than 
they were ; I found myself drawn down to the surface of 
the tiny globe on which they lived — in fact, I found myself 
one among them,, and that all I had intended to say to 
them they might with equal truth say to me. And then 
I perceived that the small globe was the earth on which 
I lived, and the great fire-globe was the sun, while the 
other orbs I had visited were the planets and their satellites. 
And when I considered that I had learned nothing about 
them which I had not known before, I was so troubled 
that I awoke — and lo, it was a dream. Yet was the 
dream not without its lesson, and its lesson w^ this : — 

6 Speak to the earth, and it shall teach thee. . . . Who 
knoweth not that the hand of the Lord hath wrought this? 
In whose hand is t\e soul of every living thing, and the 
breath of all mankind. . . . Praise ye the Lord from the 
heavens. Praise Him in the heights. Praise ye Him, 
sun and moon ; praise Him, all ye stars of light ; praise 
Him, ye heavens of heavens.' 



THE SUN. 

I saw another sign in heaven, great and marvellous. . • • Great and 
marvellous are Thy works, Lord Grod Almighty. — Kev. xv. 1, 3. 

In long past ages there were nations that worshipped the 
sun. He was their Grod ; he seemed to them as a being of 
might, ' rejoicing as a giant to run his course,' and capable 
not only of influencing the fortunes of men and nations, 
but of hearkening and responding to their prayers. A 
vain thought truly, for the creature was worshipped and 
the Creator forgotten. And yet of all the forms of religion 
in which created things were worshipped sun-worship was 
the least contemptible. Indeed, if there is any object 
which men can properly take as an emblem of the power 
and goodness of Almighty Grod, it is the sun. 

The sun is an emblem of the Almighty in being the 
source whence all that lives upon the earth derives sup- 
port. Our very existence depends on the beneficent sup- 
ply of light and heat poured out continually upon the 
earth by the great central orb of the planetary scheme. 
Let the sun forget to shine for a single day, and it would 
be with us even as though God had forgotten our existence, 
or had remembered us only to punish ; myriads of creatures 



1 2 The Expanse of Heaven. 

now living on the earth would perish, uncounted millions 
would suffer fearfully. But let the sun's rays cease to he 
poured out for four or five days, and every living creature 
on the earth would be destroyed. Or, on the other hand, 
even a worse (or at least more sudden and terrible) fate 
would befall us if an angel of wrath ' poured out his vial 
upon the sun, and power were given unto it to scorch men 
with fire.' 

Yet again, the sun is an emblem of the Almighty in 
the manner in which he bestows benefits upon us and is 
forgotten. Day after day we enjoy the sun's light and 
heat; clouds may conceal him from our view, much as 
troubles may cause us to forget God ; and the heat he 
pours out may seem sometimes insufficient or excessive, 
even as in our ignorance we are dissatisfied with the bles- 
sings bestowed by the Almighty. Yet these very clouds 
are among the good works we owe to the sun — they bring 
the rain which ' drops fatness upon the earth :' and without 
the changes of the season there would be neither the time 
of harvest nor the time of vintage. The cold of winter 
and the heat of summer, at which we often repine as ex- 
cessive, are as necessary for our wants as the cool breeze 
and the gonial warmth of spring or autumn. 

We commonly forget, also, that the sun, besides sus- 
taining us by his light-giving and heat-supplying powers, 
keeps us always near to him by that mighty force of at- 
traction which his vast bulk enables him to exert. When 
we look at the sun as he rises (even as 'the glory of God 



The Sun. 1 3 

coming from the way of the east ') how seldom is the 
thought present in our minds that in that ruddy orb there 
exists the most tremendous power, swaying not only this 
vast globe on which we live, but orbs yet vaster than she 
is, and travelling on far wider courses ; that the light and 
heat which seem to be gathering force as he rises, are in 
reality poured forth with fulness, even while as yet, owing 
to our position, we receive but little of them — nay, that 
during the dark hours of night they have been poured forth 
abundantly upon the earth ; and that so rich is the sun in 
power and beneficence, through the might of his Creator 
and ours, that our earth is nourished and supported by the 
two thousand millionth part of the heat and light which 
he pours forth ! 

It will not be unprofitable to consider a little of what 
astronomy teaches about this stupendous orb, this emblem 
of the power and goodness of the Almighty — an emblem 
infinitely feeble, it must be conceded, even when the 
teachings of astronomy are considered, for we know that 
there are countless millions of such orbs, and of yet vaster 
orbs, within the reach even of the astronomer's telescope, 
but an emblem in this respect most apt, that our feeble 
imaginations are utterly unable to conceive its splendour, 
magnificence, and power. 

This country on which we live is so minute, compared 
with the earth, that in a small globe or model of the earth 
it appears but as a scarcely distinguishable triangular 
speck. Yet we cannot conceive the dimensions of our own 



14 The Expanse of Heaven. 

country, and far less, therefore, those of the whole earth. 
Nevertheless, let it be remembered that the swiftest steam- 
ships, ploughing the seas night and day without cessation, 
require twelve weeks to complete the journey to the oppo- 
site side of the earth. Now let anyone draw a straight 
row of one hundred and seven minute circles or round dots, 
all equal in size and touching each other, and let him try 
to conceive a great cubical or die-shaped heap of little 
globes, the heap having along each edge just such a row 
of globes as has been drawn ; then the combined volume 
of all the globes forming that heap would exceed any one 
of the globes, in just the same degree that the sun's volume 
exceeds the earth's. It would, in fact, take more than 
twelve hundred thousand earths to make so large a globe 
as the sun. 

But it is not by his size that the sun's might is to be 
measured. Many comets have been far larger than the 
sun, which nevertheless have had scarcely any power of at- 
traction. The sun's might, however, is such as we might 
expect from his enormous bulk. The quantity of matter 
in the sun exceeds that in our earth no less than 315,000 
times ; and his attractive energy is proportionately enor- 
mous. If our earth, without being increased in bulk, were 
increased in density until she contained the same quantity 
of matter as the sun, the weight of every object on the 
earth's surface would be increased 315,000 times. A half- 
ounce weight, such as we use to weigh our letters, would 
press upon the earth as heavily as at present does a weight 



The Sun. 1 5 

of four and a half tons. A man's body would be crushed 
down as by the weight of 315,000 men, or more than 
20,000 tons. A body raised to a height of a single inch 
from the ground and then let fall would strike the ground 
with a velocity three times as great as that of the swiftest 
express train. 

It is the might which the sun thus possesses by virtue 
of his enormous mass which enables him to control the 
motions of the family of planets circling continually around 
him. The movements of these bodies are so beautifully 
adjusted to their distances from the great body which rules 
them, that each describes a path very nearly circular. The 
nearer globes he draws more strongly towards him, but 
their swifter motions enable them to maintain their dis- 
tance ; the farther planets travel more slowly, but at their 
distances the sun's power is correspondingly reduced. 

A cold and inert mass of matter, however, would be 
able to do all that the sun does by his mere mass, and 
yet be utterly unfit to be, like him, the ruler over a 
scheme of circling worlds. The glory of the sun is not in 
his strength alone. As Sir John Herschel has well said, 
6 Giant Size and Giant Strength are ugly qualities 
without beneficence. But the sun is the almoner of the 
Almighty, the delegated dispenser to us of light and 
warmth, as well as the centre of attraction ; and as such 
the immediate source of all our comforts, and indeed of 
the very possibility of our existence on earth.' 

If we would rightly measure the sun's activity as a 



1 6 The Expanse of Heaven. 

dispenser of God's gifts of light and heat, we must 
consider what our earth alone receives. On a glorious 
summer's day, when the air seems aglow with the sun's 
light and on fire with his heat, we are strongly impressed 
with the sense of the sun's intense activity. And yet in 
our temperate latitudes we seldom experience any ap- 
proach to the burning heats of the tropics. But even in 
the full heat of a tropical noon, the solar energy actually 
expended over the whole region which any one spectator 
can discern is but a minute part of that which he is 
exercising every instant of time on the half of the earth 
turned towards him. It has been calculated that the 
heat received by the earth during twenty-four hours 
would be sufficient to raise an ocean 260 yards deep, 
covering the whole surface of the earth, from the 
temperature of freezing water to that of boiling water. 
And this, be it remembered, is less than the 2000 
millionth part of the heat which the sun pours out into 
space during the same interval of time. Ceaselessly the 
wonderful stream of heat-waves is poured out on all sides. 
So energetic is it that the heat emitted in a single 
second would suffice to boil 195 millions of cubic miles of 
ice-cold water. Or, to take another illustration, which 
recent experience as to the value of our coal supplies will 
bring home to many of us with peculiar force — in order 
to produce by the burning of coals the supply of heat 
which we receive from the sun, there would have to be 
consumed on every square yard of the sun's surface no less 



The Stm. 17 

than six tons of coal per hour ; while, if a globe as large 
as our earth had to maintain such a supply of heat, it 
would be necessary that on every square yard of its sur- 
face more than three tons of coals should be consumed in 
every second of time. 

We cannot wonder that the source of so vast a supply 
of heat should be the scene of tremendous processes of 
disturbance. The furnace whose fires maintain the life 
of the solar system is not merely aglow with intense light 
and heat, but is in a state of fierce turmoil. The most 
tremendous conflagrations ever witnessed upon our earth 
— great fires, by which whole cities have been destroyed 
— serve to suggest something of what is going on upon 
the sun, only that all the processes of such catastrophes 
must be supposed to be intensified a million-fold. As in 
great fires there is a constant roar and tumult produced 
by the rush of air currents which the fire itself has gene- 
rated, so in every part of the sun, on every square yard of 
that enormous surface, the most hideous uproar must 
prevail as fierce cyclonic storms, bred by solar fires, rush 
with inconceivable velocity over the flaming surface. In 
the most tremendous storms known upon earth the wind 
does not travel a hundred miles per hour, and the winds 
which rage amid the flames of a conflagration are of slow 
motion compared with true hurricanes ; but the cyclonic 
storms which stir the fiery breath of the solar flames 
career often with the inconceivable velocity of more than 
a hundred miles in every second of time. And the flames 



1 8 . The Expanse of Heaven. 

themselves are on a scale altogether inconceivable by ns. 
A considerable proportion attain a height exceeding ten 
times the diameter of our earth; and some have been 
observed which have attained twice that height. But 
tremendous as are the motions taking place in the solar 
flames, even more wonderful are the effects of solar 
eruptions. By these tremendous throes matter is carried 
sometimes at the rate of four or five hundred miles per 
second 1 from the visible surface of the sun. This 
velocity not only exceeds many hundred-fold the swiftest 
motion known to us — the flight of a cannon-ball 2 — but 
even surpasses the velocity with which the swiftest of the 
celestial bodies travel on their courses. Our earth travels 
about 18 \ miles per second, Mercury more than half as 
fast again ; and one or two comets have been known to 
travel with a velocity of more than three hundred miles 
per second as they made their perihelion swoop round the 
sun. 3 But no known celestial object has ever possessed 

1 Motions at this rate have not been actually observed; but matter has 
been seen to move upwards from the surface at such a rate that a simple 
calculation shows the rate of emission to have been certainly five hundred 
miles per second, and probably very much greater. For a remarkable in- 
stance, observed by Prof. C. A. Young, of America, see my treatise on 
' The Sun ' (2nd edition), chap. vi. 

2 Light and electricity travel very much more swiftly, but in the flight 
of either there is no transmission of matter. 

3 To attain this velocity they must approach very closely to the sun ; 
and in point of fact, the great comet of 1680 (Newton's) passed so close to 
the sun that the nucleus, or centre of the head, was nearer than the summits 
of some of the largest solar prominences. The nucleus of the remarkable 
comet of 1843 passed yet closer. 



The Stm. 1 9 

a velocity approaching the tremendous rate at which 
glowing matter has been expelled from the sun's interior. 
Such are some of the marvellous processes taking 
place in that orb which to the unaided vision of man 
seems calm as the depths of a summer sky, although 

Beyond expression bright 
Compared with aught on earth, metal or stone. 

When we compare what the eye of man sees with what is 
actually going on in the sun, and consider further how 
small a way even the astronomer has advanced towards 
the interpretation of the wonderful orb which rules the 
solar system, we may well exclaim with the great apostle 
of the Gentiles, 6 the depth of the riches both of the 
wisdom and knowledge of Grod ! How unsearchable are 
His judgments, and His ways past finding out ! ' 



ao The Expanse of Heaven. 



THE QUEEN OF NIGHT. 



And God made two great lights, great for their use 
To man ; the greater to have rule by day, 
The less by night altern. — Milton. 

He appointeth the moon for seasons ; the sun knoweth his going down. 

Psalm civ. 19. 

I have spoken of the reverence with which men in long 
past ages contemplated the sun. Even before it was 
known how much we owe to the sun, how he is the source 
of nearly all the forms of force existing upon the earth ; 
and the delegated almoner of the Almighty's benevolence 
to His creatures in this and other worlds, men recognised 
in some sort the importance of the great luminary, and 
many nations worshipped him as a god. But with this 
worship there was commonly associated a subordinate 
worship of the moon ; and among some nations the moon 
was esteemed the greater deity. It is not difficult to find 
a reason for moon-worship. When we watch the moon 
for any length of time — for an hour or two, even on a 
single night — we find that she is not at rest among the 
stars. She partakes, indeed, to a considerable degree in 



The Queen of Night. 21 

that turning motion by which the whole starlit dome is 
carried from east to west around its polar axis. But she 
also has a motion of her own towards the east ; so that if 
at any hour she be seen close to some conspicuous star, it 
will be found that after an hour or two she has shifted 
her position quite appreciably towards the left — that is, 
eastwards as we face the southern heavens. And if her 
position be noted on the following night, it will be seen 
that she has passed far to the east of the star. We can 
readily understand that these movements, although they 
escape the attention of many in our time, who know little 
even of those simple celestial motions which can be de- 
tected in a few hours, 1 were quite early noticed by men 
who lived much in the open air at night. The moon's 
motions must, for instance, have been detected in very 
early times by the Chaldaean shepherds who — 

Watched, from the centres of their sleeping flocks, 
Those radiant Mercuries, that seemed to move 
Carrying through aether in perpetual round 
Decrees and resolutions of the gods. 

It was this motion of the moon, this apparent "power in 

1 The Astronomer Koyal, remarking a few years ago on a work in 
which I endeavoured to show in a simple way how the star- vault varies in 
aspect from hour to hour, and from night to night, told me that he oelieved 
quite a considerable proportion of even well-educated persons were un- 
familiar with the fact that the stars rise and set wijh the same sort of 
motion as the sun. It requires the actual light and heat of the sun, and 
the actual necessity of changing one's place if one would either remain in 
sunlight or in shade, as the case may be, to render well known the fact 
that the sun changes his place in the sky as the mid-day hours proceed. 



2 2 The Expanse of Heaven. 

her to shift her position, so as to view our earth, as it 
were, from new standpoints, which doubtless suggested to 
the ancients the idea of worshipping her as a deity. "We 
see some trace of this fancy in the words of Joli, when, 
making protestation of his integrity in the worship of God 
alone, he says, Q If I beheld the sun when it shined, or 
the moon walking in brightness, and my heart hath been 
secretly enticed, or my mouth hath kissed my hand ' l 
(that is, if he had worshipped these heavenly bodies), 
6 this also were an iniquity to be punished by the Judge ; 
for I should have denied the Grod that is above.' 

Although the moon does not render such important 
services to the earth as the sun does, yet even viewed in 
this aspect, there is much in the moon's action which may 
help to explain the worship once paid to her. 

The moon has been appointed for seasons; the Al- 
mighty spake — 

Let there be Lights 
High in th' expanse of Heaven, to divide 
The day from night ; and let them be for signs 
For seasons, and for days, and circling years ; 
And let them be for lights, as I ordain 
Their office in the firmament of Heav'n. 



1 We had a curious illustration of this Eastern method of expressing 
reverence in the comments made upon the manner in which the Shah of 
Persia acknowledged the cheers of the Germans. An English writer de- 
scribed the action as scooping with the hand as if to lift water, which was 
forthwith carried to the mouth ; and, oddly enough, this writer mistook the 
motion as intended to imitate our military salute. It really symbolised the 
act of one who lifts the hem of another person's garment to his lips in 
token of respect. 



The Qtieen of Night. 23 

Our month, although not according with the lunar month, 
nevertheless had its origin in the study of the lunar 
motions, as indeed the name of this interval of time 
sufficiently indicates. I need hardly remind the reader, 
again, of the part which the moon takes in fixing the 
dates of the Jewish movable festivals, while our own 
movable festivals in like manner depend on the moon's 
motions, the Paschal full moon determining Easter Day, 
and the other movable feasts following accordingly. 

The benefits rendered by the moon as a light-giver 
at night need hardly be insisted upon. Whewell has 
well remarked, in his Bridgewater Treatise, that ' a person 
of ordinary feelings, who on a fine moonlight night' 
(moonlit is the more correct expression) 6 sees our satellite 
pouring her mild radiance on field and town, path and 
moor, will probably not only be disposed to " bless the 
useful light," but also to believe that it was " ordained " 
for that purpose.' The great mathematician Laplace 
adopted an opposite view. Setting himself boldly, one 
may say defiantly, against the wholesome belief that there 
is method and design in the works of the Creator, he 
sneers at the belief of < those partisans of final causes who 
have imagined that the moon was given to the earth to 
afford light during the night.' This c cannot be so,' he 
remarked, 6 for we are often deprived at the same time of 
the light of the sun and the moon,' and he proceeds to 
show how the moon might so have been placed as to be 
always ' full,' in other words, always opposite the sun, so 



24 The Expanse of Heaven. 

that the arrangement described by Milton as prevailing on 
the first day of the moon's existence might have continued 
for ever : — 

Less bright the moon, 
But opposite in levell'd west was set 
His mirror, with full face borrowing her light 
From him ; for other light she needed none 
In that aspect ; and still that distance keeps 
Till night, then in the east her turn she shines 
Eevolv'd on Heav'n's great axle ; and her reign 
With thousand lesser lights dividual holds, 
"With thousand thousand stars, that then appear'd 
Spangling the hemisphere. Then first adorn'd 
With her bright luminaries that set and rose, 
Glad evening and glad morn crown'd the fourth day. 

In fact, Milton would seem to have entertained the belief 
that this state of things not only characterised the first 
day of the moon's creation, but continued until the Fall ; 
for in the tenth book, after describing how the sun was 
set ' so to move, so shine 

As might affect the earth with cold and heat 
Scarce tolerable/ 

he proceeds to indicate some change in the moon's mo- 
tions — 

To the blank moon 
Her office they prescribed — 

a new office, so differing from her former office as to form 
fit part of 

Growing miseries, which Adam saw 
Already in part. 

Laplace's device, however, involves the necessity of a 



The Queen of Night. 25 

moon of different size and distance. He shows how a 
moon about four times as far off as our moon really is 
would revolve around the earth in the same time as the 
sun apparently does, and would thus present always a full 
aspect — if originally placed opposite the moon. It is a 
slight objection to this imagined state of things that, for 
Laplace's moon to appear as large as ours, it should have 
a diameter about four times as great, and be in fact 
as large, as our earth, while the motions assigned to it 
require that it should not be more massive than the present 
moon. Thus it would have to be made of material 
exceedingly light, about sixty times lighter than the 
present substance of the moon. This would be about 
seventeen times lighter than water, and more than four 
times lighter than cork. We know of no such substance, 
and therefore it seems idle to discuss further Laplace's 
daring notion. But this also may be remarked — that 
although such a moon as he described might for a very 
long period continue always exactly opposite the sun, yet 
in the course of time this moon would gradually fall away 
from that position ; for the motions both of the earth and 
of this imagined moon could not possibly remain abso- 
lutely uniform. Thus at length a time would come when 
this moon, instead of being always 'full,' would be 
always 'new,' that is, always on the same side as the 
sun, and so give no light at all, even if she did not 
eclipse the sun. 

On the whole, we may be content to accept the moon 



2 6 The Expanse of Heaven. 

as we find her, and to < bless her useful light,' without 
being particular to enquire whether another moon might 
not have given us more light or under more convenient 
conditions. Indeed, the astronomer would be content 
with much less moonlight than we actually have, since the 
moon's light is very unfavourable for the study of the 
stars. Not only do the greater number of lucid stars (so 
astronomers term those which can be seen with the naked 
eye) disappear when the moon is bright, but the range of 
the telescope is proportionately reduced. The astronomer 
cannot hope to penetrate the star depths as effectually 
during the moonlit hours as at other times. Delicate 
objects like comets and star-cloudlets can scarcely be 
studied at all when the moon is shining. 1 And the astro- 
nomer must certainly contemplate with any feeling but 
admiration the arrangement proposed by Laplace. As it 
is, there is a sufficient approach to the state of things 
described in the article on 'Life within a Cluster of 
Suns' 2 to make 'the want of night' no imaginary mis- 
fortune to the astronomer. 

1 None but those who have tried tho experiment can believo how seldom 
tho astronomer has a really dark clear night, with tho atmosphero in good 
condition for observing. I have myself had occasion to note this circum- 
stance somowhat markedly ; for I have- desired to gauge the star depths 
with a very fino reflecting telescopo kindly placed at my disposal by Lord 
Lindsay. .But when I set aside those nights when twilight continues all the 
night, those whon the moon shines, cloudy or hazy nights, and nights 
when the air is disturbed and unfit for telescopic work, I find the time 
really available for this special work amounts only to a few hours in each 
year. 

8 Soo p. 211, * A Cluster of Suns.' 



The Queen of Night. 27 

One remarkable feature of the moon's service as alight- 
bringer has been regarded as specially suited to subserve 
the wants of man, I refer to the phenomenon called the 
harvest moon. Without entering into explanations which 
would be out of place in these pages, I may simply state 
that in autumn the moon for several days, about the time 
of ' full,' rises night after night very nearly at the same 
time, so as in fact to remain above the horizon nearly all 
night. This is manifestly convenient to those engaged 
in harvesting operations, insomuch that, as Ferguson 
states, ' Farmers, better acquainted with the facts than 
astronomers till of late, gratefully ascribed the early 
rising of the full moon at that time of the year to the 
goodness of God, not doubting that He had ordered it so 
on purpose to give thein an immediate supply of moon- 
light after sunsetj for their greater conveniency in reaping 
the fruits of the earth.' 

It is clear that the action of the moon in raising a 
great tidal wave is of important service to the inhabitants 
of the earth. It is probable, indeed, that the tides are 
absolutely necessary to preserve the ocean watera in a 
healthy condition by continual movement. But the 
tidal wave discharges special services exceedingly im- 
portant to mankind. The building and launching of ships 
would be rendered a task of much greater difficulty if it 
were not for the alternate rise and fall of the sea. No 
one, again, who is familiar with life at the seaside, and 
particularly in cities placed near the mouths of great 



28 The Expanse of Heaven. 

tidal rivers, can fail to recognise abundant evidence of the 
importance of the variation of the sea's level in many 
nautical and commercial processes. 

But perhaps the greatest benefit conferred by the moon 
on mankind is one which few are aware of. It may truly be 
said that each year hundreds of lives that would otherwise 
be endangered are rendered safe by her means. It is known 
that when our seamen pass far beyond the sight of land, 
their safety depends on their observations of the celestial 
bodies. By such observations they are enabled to learn 
where they are, or, in technical words, their latitude and 
their longitude — that is, their distance north or south of 
the equator, and their distance east or west of some fixed 
station, such as Greenwich. Now their latitude is easily 
determined by observations of the sun or stars, whose 
altitude when due south depends solely on the latitude. 
But it is different with the longitude ; for when we travel 
due east or west we do not find the apparent paths of the 
sun and stars changing at all. The only change which 
lakes place is in the time at which the celestial bodies rise 
and set. It is of course noon when the sun is due south, 
wherever the observer may be (at least in our northern 
hemisphere). But it is not Greenwich noon, unless the 
observer is due north or south of Greenwich. If he is 
east of Greenwich it is past Greenwich noon when it is 
noon for the observer's station, and if he is west of 
Greenwich it is before Greenwich noon when the sun is 
due south. If he has a clock showing Greenwich time 



The Queen of Night. 29 

he can thus learn how far east or west he may be. Now 
the moon, properly observed, serves for the seamen the 
part of a clock which can never go wrong. The stars 
serve as the marks on the great dial-plate of the heavens, 
by which the position of the moon — the moving hand — 
can be determined with the utmost nicety. Calculations 
are then applied to show precisely where the moon would 
be seen among the stars if the observer were at the centre 
of the earth instead of at his actual station. And then a 
reference to the Nautical Almanac shows precisely what is 
the Greenwich time. Thence the observer learns how 
far east or west he is of Greenwich. And often, after 
many cloudy nights have passed, the observation of the 
moon has shown the sailor that owing to currents and 
misjudged rate of sailing, he has been far out in his 
reckoning ; and he has been saved by the moon from a 
great danger. So that we may find a new meaning in 
the words of the inspired Psalmist — c They that go down 
to the sea in ships, that do business in great waters ; 
these see the works of the Lord, and His wonders in the 
deep.' 



II. 

I have hitherto considered the moon with reference 
chiefly to the services which she renders to our earth. I 
showed that, as a subordinate light-giver, as a measurer of 



30 The Expanse of Heaven. 

time, as chief ruler of the tides, and, lastly, as a celestial 
index which shows the experienced seaman where he is 
on the wide expanse of ocean, the moon subserves most 
important purposes to the inhabitants of the earth. I pro- 
pose presently to consider the moon in another aspect ; to 
enquire into her actual condition as a member of the 
solar system, and to describe briefly the interesting cir- 
cumstances which have been ascertained by means of the 
telescopic scrutiny of her surface. Before passing, how- 
ever, from the former branch of my subject, I would make 
a few remarks on the convenience of the present arrange- 
ment as compared with that which the great mathema- 
tician and astronomer Laplace suggested as better suited 
for our requirements. 

It will be remembered that Laplace showed how a 
moon might so circle around the earth as to be at 
all times exactly opposite the sun, and therefore always 
'full,' rising also always when the sun set and setting 
when the sun rose. I mentioned in my last paper certain 
difficulties attending this arrangement even when con- 
sidered with reference to the particular result which it was 
designed to "bring about. I also touched on the incon- 
venience of some of the results which would have followed 
from it, and particularly on the loss we should sustain if 
we never had a perfectly dark night. But it is even more 
important to notice how seriously all the other services 
rendered by the moon to ourselves would have been 
affected if the moon's motions had been those devised so 
ingeniously by Laplace. 



The Queen of Night. 31 

Let it be remembered that to be always opposite the 
sun the moon must circle round the earth in the same 
time as the sun, or once a year. Thus the moon would 
no longer afford any subordinate time-measures. It is 
manifest that this would be a decided loss. 

Again, the sun and moon at present join in controlling 
the tides, in such a way that when the moon is opposite 
the sun or on the same side as the sun, we have a tide 
resulting from the combined action of the sun and moon ; 
while when the moon is half-way between these positions, 
as at first and third quarters, we have a tide which is 
merely the excess of the lunar tide-wave over the solar 
tide-wave. If the wave produced under the former cir- 
cumstances be represented by the number 7, then the 
wave under the latter circumstances will be represented by 
the number 3 ; for the solar and lunar tide-waves are as 
2 to 5, and they always coalesce so as to produce a single 
but variable tide-wave. Now it is clear that this varia- 
tion of the tide-wave adds importantly to the service 
which the tides render to man. It is extremely con- 
venient to have occasional very high tides, while it would 
manifestly be inconvenient to have the range of the tidal 
wave always at its greatest value. Now, if Laplace's 
arrangement prevailed we should have the moon always 
co-operating with the sun, for they work together equally 
whether they be on the same or on opposite sides of the 
earth. Thus we should always have ' flood ' tides, or 
rather we should know of no such differences as now dis- 



3 2 The Expanse of Heaven. 

tinguish flood-tides from neap-tides. This would be a 
second serious loss. 

And lastly, as to the service which the moon renders 
to seamen by her motions among the stars, it is easily 
shown that she would at once lose a great part of her 
value iu this respect if she circled round once a year 
instead of once a month. She would move then with less 
than a twelfth of her present rate of motion (for there 
are more than twelve lunar months in a year). Now this 
would correspond almost exactly to the case of a clock 
which had lost its minute hand, so that we had to de- 
termine the time from the position of the hour hand. 
Wc 4 know that owing to the very slow motion of the hour 
hand we could never tell the time within several minutes 
by its means. We judge always by the minute hand. 
So with the moon. Her comparatively rapid motion 
enables the sailor to determine the time (not the time 
of day, but what may be called 'earth-time') very 
closely 5 whereas if she moved with only one-twelfth part 
of her present motion, she would be practically useless as 
a time-indicator. Nor let the reader imagine that the 
difference of her value in this respect would be insignifi- 
cant in its effects. Time in this case means position; an 
error of time means an error of position ; and an error 
of position means danger. The danger is greater or less 
according as the error is likely to be greater or less. 
Now, unfortunately, a very small error of time corre- 
sponds to an error of distance quite sufficient to involve 



The Queen of Night. 33 

very great danger. Let us suppose, for instance, that a 
ship is in latitude sixty degrees — that is, somewhat 
farther northwards than the north of Scotland — and that 
she is making her way towards the American coast ; now 
suppose that observations of the moon have given the 
time very nearly right — say only half a minute wrong — and 
let us enquire how far wrong the estimated place of the 
ship would be. A degree in sixty north latitude contains 
half as many miles as at the equator, where, as we know, 
each degree contains sixty ' knots,' or nautical miles, or 
about sixty-nine common miles. Hence in latitude sixty 
north, each degree contains about thirty-four and a half 
miles. The earth turns through fifteen degrees each hour, 
and therefore through one degree in four minutes. So 
that an error of four minutes in the time would be equi- 
valent to an error of thirty-four and a half miles in the 
determination of the ship's place. Half a minute would 
give an error, therefore, of about four and a half miles, 
quite enough to cast a ship upon some iron-bound shore 
when her captain judged that she was still at a safe dis- 
tance. 1 It will be seen, therefore, how serious would be 

1 That erroneous notions may not be suggested as to the way in which 
our seamen actually provide against such dangers as are here indicated, I 
must remark that in point of fact there is no reliable method for determin- 
ing a ship's place at sea with such accuracy that a captain could approach 
shore confidently (at night, for instance) within a few miles. All that he 
can expect from observation is such an approach to accuracy that until he 
is at a moderate distance from shore, no special look-out for land need be 
maintained. Of course the more accurate his means of determining true 
earth-time, the shorter will be the period during which (if he is worthy of 



34 Tlie Expanse of Heaven. 

the mischief if all such errors as must inevitably arise in 
such cases were increased twelve-fold. 

I cannot but think that the lesson we may derive from 
these considerations is a very instructive one. Let it be 
remembered that Laplace was a man of most remarkable 
powers. As a mathematical astronomer he comes next 
after Newton, of whom it has been justly said that he sur- 
passed the whole human race in mental power. Laplace 
has not been judged to have spoken unadvisedly when, 
referring to Newton's work, he said that Newton was for- 
tunate in being the earlier born, implying that he himself 
had the power to have discovered the great law of gravita- 
tion, had not Newton first accomplished the work. This, 
which would have been regarded justly as arrogance in 
another, has not been so imputed to Laplace even by those 
who question whether Laplace in Newton's place would 

the trust reposed in him by crew, passengers, and employers) he will take 
no rest, and relax not one instant from watchfulness. To show what could 
be done if there were perfect means of determining the time, the following 
narrative may be cited : — When the ' Great Eastern ' is carrying a telegraph 
cable across the Atlantic, her captain of course knows the true Greenwich 
time within a single second, for it is flashed to him from Valentia. He can 
therefore determine his true place with great accuracy. Now it chanced 
that on one occasion the captain of the ' Great Eastern,' while thus in tele- 
graphical communication with Greenwich through Valentia, had occasion to 
search for a buoy which had been left floating (attached to a sunk cable) in 
a particular latitude and longitude. He made for the spot according to his 
calculated latitude and longitude, and (according to the account) after the 
final directions had been given to the effect that the ship should follow a 
certain course for a certain time, he went below to examine a chart. "When 
the time came he was about to go on deck, hoping to have made his course 
so truly that the buoy would be in sight; but at that very instant the ship's 
side was struck by the buoy. 



The Queen of Night. 35 

have done so much as Newton actually achieved. This is 
the highest praise which could be given to any astronomer 
short of saying that he was Newton's equal. Now see how 
the great mathematician failed when he employed his 
powers to show in what way the work of the Almighty 
might be improved. He showed how a certain advantage 
might have been obtained had a certain special arrange- 
ment been adopted. So far all was well. But he omitted 
to observe how much more would be lost than would be 
gained by the proposed alteration. His scheme was con- 
ceived in the spirit of the remark made by Alphonsus, 
king of Portugal, who, speaking of the system of the uni- 
verse as understood in his day, said that if the Almighty 
had consulted him when the universe was about to be 
created, he could have given useful advice. Alphonsus 
was in one sense right, since his remark, ugly though it 
sounds, was really intended to imply no more than that, 
in his opinion, astronomers had not in his day discovered 
the true system of the universe. But had Laplace been 
consulted when the moon's position and path were designed 
(to use such words for want of better), and if his advice 
had been adopted, we should have had a moon which would 
have subserved but one out of four highly important ser- 
vices actually rendered to us by her. Well might Laplace 
have been answered by the Almighty, even as of old He 
.answered Job out of the whirlwind, 'Who is this that 
darkeneth counsel by words without knowledge ? Gird 



36 The Expanse of Heaven. 

up now thy loins like a man ; for I will demand of thee, 
and answer thou me. Where wast thou when I laid the 
foundations of the earth ? declare, if thou hast under- 
standing. Who hath laid the measures thereof, if thou 
knowest ? or who hath stretched the line upon it ? Where- 
upon are the foundations thereof fastened ? or who laid 
the corner stone thereof; when the morning stars sang 
together, and all the sons of God shouted for joy ? . . . 
Hast thou commanded the morning since thy days ; and 
caused the dayspring to know his place. . . . Knowest 
thou the ordinances of heaven ? canst thou set the dominion 
thereof in the earth ? . . . Wilt thou also disannul my 
judgment ? wilt thou condemn me, that thou mayest be 
righteous ? ' 

I will draw this portion of my subject to a conclusion 
by calling attention to one feature of the moon, which, 
though it does not tend in any way to increase the 
comforts of the human race, has been of great importance 
so far as their acquisition of knowledge has been concerned. 
I refer to the near agreement in point of apparent size 
between the sun and the moon, two globes which differ so 
remarkably as to their real dimensions. The agreement 
is so close that as the sun and moon slightly vary in 
apparent size, according to their slightly varying distance^ 
the moon looks sometimes slightly greater and sometimes 
slightly less than the sun. Now, it is easily seen that if 
this relation had not existed — and it is in a sense merely 
fortuitous, not existing in the case of any other planet 



The Qtceen of Night. 37 

which has a moon — we should know very much less than 
we actually know about our sun. If the moon had a disc 
much smaller than the sun's there would never be a total 
eclipse of the sun, and all those wonderful objects which 
make their appearance when the sun is totally eclipsed — 
the coloured prominences and the sierra, the glowing 
inner corona, and the radiated fainter glory which lies 
outside the corona — would have been altogether unknown 
to us. But we should scarcely have learned more if the 
moon had had a disc much larger than the sun's. For in 
that case when a total eclipse began, all the region round 
the sun, except that close to the part of the sun's face 
concealed last, would be hidden by the moon's much 
larger disc. At the middle of totality, the red promi- 
nences and sierra, as well as all the brighter part of the 
corona, would be altogether concealed from view. And, 
lastly, at the end of totality the same state of things 
would prevail as at the beginning, only now it would be 
close to the part of the sun just about to appear, that for 
a moment or two the red prominences would be visible. 
Manifestly it would be quite hopeless under such circum- 
stances to attempt to obtain any satisfactory observations 
of the solar surroundings. We now see during totality 
the complete ring of prominences for two or three minutes, 
and the whole of the corona is shown. Even as thus 
shown it has been sufficiently difficult to ascertain the 
nature of these objects. But with a moon much larger 
than ours we could have learned scarcely anything 



38 The Expanse of Heaven. 

respecting them, and with a moon much smaller we 
should have known absolutely nothing of the solar 
appendages. 



III. 

With how sad steps, O moon, thou climb'st the sky, — 
How silently and with how wan a face ! — Wordsworth. 

In this, the third and concluding part of my essay on the 
Queen of Night, I propose to consider her not as a mere 
satellite or attendant on the earth, but as a planet or other 
world, possibly, though not probably, an inhabited world. 
It may seem strange, perhaps, to some of my readers 
to find the moon spoken of as a planet. We are so accus- 
tomed to view the moon as a relatively small body circling 
around our earth, and directly subordinate to the require 
ments of her inhabitants, that it is only by an effort of 
the imagination that we can rise to the conception of her 
real position in the scheme of worlds circling around the 
sun. But in reality the moon is governed in her motions 
mainly by the sun ; she circles around him rather than 
around the earth, though, viewed from our terrestrial 
standpoint, she appears to obey the earth's influence 
more directly than the sun's. If the moon could be 
watched from some distant point whence the whole solar 
system could be seen, her course around the sun would be 
seen to resemble that followed by a planet. This course 



The Queen of Night, 39 

may be described as nearly circular, and slightly eccentric, 
insomuch that while her mean distance is about ninety- 
one millions of miles, she is some 1,500,000 miles nearer 
to the sun in December and January than in June and 
July. This, let it be noticed, is precisely what we should 
say of the earth's path ; and all that has to be added to 
the description of the moon's path is that, in a period of 
about four weeks, she passes alternately farther from the 
sun and nearer to him than her mean path by about 
240,000 miles, a mere trifle, it will be seen, compared with 
the dimensions of her actual path round the sun. Nor is 
it true, as I have sometimes seen stated in books on 
astronomy, that the moon follows a spiral or twisted path, 
owing to her movement around the earth, combined with 
her movement round the sun. If a perfectly exact repre- 
sentation of the moon's path were made in very fine wire, 
on a tolerably large scale, it would require the nicest 
scrutiny to distinguish the wire curve from a perfect 
circle. Again, if we represented' the earth's path by a 
wire circle a foot in diameter, and one-thirtieth l of an 
inch in thickness, the moon's path would be wholly 
included within the substance of that wire, passing alter- 

1 Rather less than a thirtieth, more exactly a thirty- third part. The 
reader should take an ordinary foot-rule, divided into inches and tenths of 
an inch; then one-third of one of these tenths will correspond to the 
greatest range of the moon within and without the earth's path, where 
this path is represented by a circle a foot in diameter. On the same scale 
the sun would be represented by a little globe rather less than two-thirds 
of the tenth of an inch in diameter, and about one-tenth of an inch from 
the centre of the circle. 



40 



The Expanse of Heaven. 



nately close to its inner side and to its outer side, at 
points dividing the ring nearly into twenty-five equal 
parts. 

We see, then, that so far as the moon's path is con- 
cerned, she may be regarded as a planet. Nor is she 
markedly inferior in bulk to some of the other planets 
forming the sun's inner family, consisting, as we know, of 
Mercury, Venus, the Earth and Moon, and Mars. She is 
certainly the smallest of this family, but compared with 
Mercury, she is not so small by far as Mercury is compared 
with the earth, and she is not much smaller compared 
with Mars than Mars is compared with the earth. This 
will be easily seen from the following numbers, which 
represent the volumes of the five planets which circle 
nearest to the sun, arranged in order of magnitude : — 



The Earth .... 


. 1000 


Venus 


. 855 


Mars 


. 168 


Mercury .... 


58 


The Moon .... 


20 



And it must be remembered also that the absolute dimen- 
sions of the moon are by no means insignificant The 
moon's diameter is about 2,160 miles in length ; she has 
a surface of 14,600,000 miles, and a solid content of 
about 10,000 millions of cubic miles. If we consider her 
surface as the feature by which she is most readily brought 
into comparison with our earth, then it^s to be noted 



The Queen of Night. 



4i 



that the earth's surface only exceeds the moon's about 13^ 
times, and the moon's surface is fully as large as Africa 
and Australia together, or nearly as large as North and 
South America without their islands. 

In mass or quantity of matter the moon is somewhat 
more markedly inferior to the other four planets, as the 
following list of numbers, showing the relative mass of 
the five planets, sufficiently indicates : 

The Earth 
Venus • 



Mars . 
Mercury 
The Moon 



1000 

885 

118 

65 

12 



But still, it will be seen, the earth exceeds Mercury, in 
mass as in volume, to a greater degree than Mercury 
exceeds the moon ; and Mars holds much the same relative 
position between the earth and the moon in this list as in 
the list of numbers representing the volume of the five 
planets. Moreover, the quantity of matter in the moon 
cannot be looked upon as absolutely insignificant, when 
we consider that the average density of the moon is more 
than three times as great as the density of water, and 
that she contains, as above mentioned, about 10,000 
millions of cubic miles of matter. If the moon could be 
weighed against a quantity of water — say in some vast 
balance placed on the surface of the sun or of some other 
very large and massive orb — it would be found that about 



42 The Expanse of Heaven. 

34,500 cubic miles of water would be required to counter- 
balance the moon's weight. 

There is one circumstance, however, in which the 
moon shows a sort of dependence upon the earth, produc- 
ing a very striking distinction between her and the other 
planets. She turns round on her axis in such a way as 
always to turn the same or nearly the same face towards 
the earth. As she turns uniformly, but does not travel at 
a quite uniform rate, and as she also turns on a slightly 
inclined axis, she sometimes shows a little more of her 
eastern and western sides, or again of her northern and 
southern sides, than at other times ; but her average rate 
of turning is absolutely identical' with her average period 
of motion round the earth, and accordingly she never 
sways more than a certain portion of her surface into 
view or out of view by these libratory or balancing motions. 

Now this rate of rotation is exceedingly slow. For we 
know that the moon takes about a month in circling 
round the earth ; and therefore she takes about a month 
in turning upon her axis. In other words, the moon's 
day lasts about four of our weeks ; and if we suppose it 
divided as we divide our day, into twenty-four equal parts, 
then each of these parts lasts more than one of our days — 
in fact, a lunar hour lasts nearly 29^ of our hours. Day- 
time lasts on the average rather more than a fortnight of 
terrestrial time ; and night lasts as long. Here, then, 
there is a very singular contrast between the state of 
matters on the moon and on our earth. 



The Queen of Night. 43 

The contrast is rendered even more striking by the 
circumstance that the lunar year is shorter than our year. 
This will seem strange at first sight, because I have said 
that the moon travels round the sun on a path almost 
identical with the earth's, and of course in the same time. 
Now, we all know that our year is the time occupied by 
the earth in. going once round the sun : and it might 
seem that the lunar year must necessarily be the period 
occupied by the moon in going once round the sun, this 
period being our common year. But a peculiarity which 
very slightly affects our own year of seasons, 1 making it 
in reality more than twenty minutes shorter than the 
year of circling round the sun, affects the moon's year in 
a much greater degree, insomuch that while the lunar 
year of circling round the sun lasts, like ours, 365 days, 
six hours, and nine minutes, the lunar year of seasons 
lasts only 346 days, fourteen hours, and thirty-four 
minutes. 

It follows that there are not quite twelve lunar days 
in a lunar yean Each of the four seasons lasts rather 
less than three days. 

But the seasons are also very slightly distinguished 
one from the other. Lunar winter differs from lunar 
summer no more than on our earth the 16th of March 



1 The peculiarity is in fact a swaying of the earth's axis like the slow 
reeling of a mighty top, each reel occupying about 25,866 years. The cor- 
responding motion of the moon's axis is completed in about 18 years and 7 
months. 

3 



44 The Expanse of Heaven. 

differs from the 26th, or than the 27th of September 
differs from the 19th. 

If the contrast between winter and summer is slight, 
however, the contrast between day and night is very re- 
markable. In order clearly to understand this, we must 
not only consider the great length of the lunar day, but 
the condition of the moon as respects those circumstances 
which on our own earth temper the mid-day heat and the 
cold of midnight. In the telescope the moon appears to be 
a perfectly waterless globe, her arid surface being covered 
with ring-shaped mountains, mountain-ranges, peaks, 
fissures, and rocks, except in certain regions, called seas, 
where the surface (really solid) is apparently quite smooth. 
It was formerly supposed that these smooth regions, which 
are rather darker than the rest of her surface, are seas ; 
and, by a singular perversity, astronomers who have been 
but too ready to introduce new names among the constella- 
tions have continued to call these regions ' seas,' long after 
it has been demonstrated that they are land-surfaces. It 
is certain, then (at least as respects the side of the moon 
turned earthwards), that none of those beneficial effects 
which result on earth from the presence of extensive 
water-covered regions can be produced on the moon. No 
clouds can temper the heat of the lunar day, or at night 
prevent the too rapid escape of the heat which had been 
garnered up, so to speak, in the daytime ; nor can any of 
those more subtle processes take place which result from 
the presence in our air of the unseen vapour of water. 



The Queen of Night. 45 

Nor is this all. So far as we can judge, the moon has no 
air ; at least no sign of air has ever been perceived by- 
astronomers, even when they have applied the most 
delicate tests by means of the most powerful instruments. 
It is certain at any rate that whatever air there may be 
is very small in quantity compared with our air. Thus in 
the daytime the sun's heat is poured down with unmiti- 
gated effect upon the moon's surface, which during the 
long fortnightly day must be positively broiled by the 
solar rays ; while at night, or rather so soon as night 
begins, the heat all passes away into space, and then for 
hour after hour of the long lunar night an intensity of 
cold must prevail far exceeding the bitterest cold of our 
Arctic and Antarctic regions. 

It has been thought that on the farther side of the 
moon a different state of things may prevail, that oceans 
and an atmosphere may be there, and, possibly, living 
creatures not differing very greatly from those on our 
earth. I must confess that the evidence on which this 
opinion has been based does not appear to me convincing. 
And, apart from this, we see far enough round the other 
side to detect some signs of air, if not of oceans, if any 
existed there. If the whole surface of the moon be re- 
presented by the number 1000, the parts we see at one 
time or another amount in all to 589, while the parts 
never seen amount in all but to 411. Then there is 
this consideration, which to most minds will not seem 
without weight : — The part of the moon turned earth- 



46 The Expanse of Heaven. 

wards is, of course, the only part whence the earth can be 
seen. Now, it would certainly be a singular, and one may 
even say an unwise, arrangement (at any rate, the wisdom 
of the arrangement is not manifest to us) by which the 
inhabitants of the moon should be so confined to a certain 
lunar region as to . be deprived of all opportunity of 
beholding the beautiful spectacle presented by our earth, 
as, with varying phases, she shows her huge disc (more 
than thirteen times larger than the moon's as seen by us), 
with its continents and seas, passing in orderly sequence 
into and out of view, with its aspect changing as the 
seasons progress, and with all the other charming phe- 
nomena which she must present to lunar inhabitants, if 
any such there are. 

More reasonable appears the conclusion that either 
the moon is not now inhabited, or, if she is inhabited, that 
it is by classes of beings quite unlike any with which we 
are familiar. 



THE EVENING STAB. 

Now glows the firmament 
With living sapphires ; Hesperus, that leads 
The starry host, rides brightest. — Paradise Lost. 

In April there shines towards the west a star so far 
surpassing all others in the heavens in brightness, that 
it might well be believed to be the most important of all 
the orbs discernible by us. It is Hesperus, the star of 
the evening, the planet Venus ; and, in reality, so far 
from being the largest of all the orbs we see, there are 
but two celestial bodies, besides the Moon, which are 
smaller than this beautiful planet. The planet Jupiter, 
which can now be seen at midnight, and is far inferior 
in brightness to Venus, is in reality a globe surpassing 
her more than thirteen hundred times in volume. And 
even Jupiter sinks into utter insignificance by comparison 
with the least of the fixed stars ; while the splendid Sirius, 
which shines less brightly far than Jupiter, probably sur- 
passes Venus in bulk more than a thousand millions of 
times. 

Yet Venus is a globe of great magnitude when we 
compare her with all terrestrial measures of size. That 
star which seems like a very bright but tiny light in the 



48 The Expanse of Heaven. 

sky, has, in reality, a surface which our swiftest modes of 
travelling would enable creatures like ourselves to survey 
only in a long period of time. Supposing that surface 
ocean-covered, then a vessel travelling as fast as our 
swiftest steamers would be more than two months in 
completely circumnavigating it. It gives a signal proof 
of the mistaken ideas we are apt to form, to look at that 
bright point of light now illumining our evening skies, 
and to consider that a steam vessel travelling around it, 
and ploughing the waves so swiftly that the sea-foam 
would dash in great white masses over its prow, would have 
to pursue it's course unceasingly for seventy or eighty 
days in order to complete the circuit of that seemingly 
minute body. 

It may be said without noticeable inaccuracy that 
Venus is a globe as large as our earth. Some telescopic 
measures have led astronomers to the conclusion that she 
is larger than our earth, while others (and these are 
commonly regarded as the best) appear to show that she 
is somewhat smaller than the earth. She has no moon, 
and is in that respect inferior to her sister planet Terra. 
But in many circumstances she so closely resembles the 
earth, that it is difficult to imagine that she is not, like 
the earth, an inhabited world. She is nearer to the sun, 
indeed, in the proportion of about 73 to 100, and conse- 
quently she receives more light and heat than the earth, 
in the proportion of about 100 times 100 to 73 times 73, 
or nearly 2 to 1. This seems at first sight to render 



The Evening Star. 49 

her unfit to be the abode of living creatures ; for even in 
our temperate latitudes the increase of the sun's light and 
heat in a twofold degree would undoubtedly destroy nearly 
all the forms of life now existing on the earth. But we 
are apt to forget that the forms of life we are accustomed 
to are not necessarily the only possible forms of life. It 
is almost impossible to say under what conditions life is 
possible or impossible. Men of science have lately been 
taught this in a very striking manner. For, judging by 
what they know of the state of things at the bottom of 
the deep sea, they concluded that there could be no living 
creatures there. They reasoned that the pressure exerted 
by the water would crush the life out of any known 
creature, which was unquestionably true. A piece of the 
hardest and densest wood, sunk to those depths, has the 
water literally forced into its very substance, and the 
tremendous mail of the crocodile, or the thick skin of the 
rhinoceros, would be unable to resist a tithe of the enor- 
mous pressure exerted by the water at the bottom of deep 
seas. Yet it is now known that creatures not only exist 
down there, but that, notwithstanding the great darkness 
which must prevail there, these creatures are provided 
with the means of seeing. So unlike are they to all other 
creatures, however, that they are unable to live out of 
their native depths, and when dragged up by the dredges, 
they burst asunder and are killed long before reaching 
the surface. This should teach us that although it may 
be proved that in some inaccessible world, like Venus, or 



50 The Expanse of Heaven. 

any of her fellow planets, the conditions which prevail 
are not such as would be convenient to terrestrial creatures, 
or are even such that no creatures known to us could endure 
them even for a few minutes, life may nevertheless exist. 
It is indeed tolerably certain that if there are living 
creatures in Venus (as for my own part I little doubt), and if 
among these creatures there are any which possess reasoning 
powers such as ours (which is not so certain), it must appear 
to such reasoning beings in Venus at least as difficult to 
understand how our earth can be inhabited as we find it 
to conceive what nature of creatures they may be which 
exist in Venus. 

The year of Venus is much shorter than ours, amount- 
ing in fact only to 225 days, or rather less than 1\ months. 
So that if we suppose the year to be divided into four 
seasons as with us* each of these seasons lasts rather 
less than two of our months. But with the tremendous 
heating and illuminating power which the sun must 
exert on Venus, the progress of vegetation must be much 
more rapid than on our own earth, and therefore so long a 
year is not required. Yet it must not be imagined that 
the short year of Venus of itself renders the condition of 
the planet unlike that of any part of our earth. There 
are regions on our earth where the hottest and coldest 
seasons are not separated as they are here in England by 
six months, but by three. This happens in the equatorial 
regions, where the seasons we call spring and autumn are 
the hottest part of the year, while the seasons we call 



The Evening Star. 5 1 

summer and winter are the coolest, or rather (since cool- 
ness, at least by day, is unknown in equatorial regions) 
are the least warm seasons of the year. And I have often 
thought, in connection with the subject of life in other 
worlds, that if the inhabitants of the earth were in some 
way prevented from travelling to other countries than 
those in which they were born, but were able to learn 
something of the climate of other regions, they would 
be apt to believe that life was quite impossible anywhere 
but in their own latitudes. For instance, if we did not 
know that the torrid zone was inhabited, and could not 
visit that region, but knew nevertheless how tremendous 
the heat is there, how short the interval from greatest to 
least heat, and so on, how ready we should be to believe 
that neither animal nor vegetable life can exist there. And 
in like manner as to the Arctic regions. Supposing we 
knew only that there are parts of the earth where the sun 
is sometimes unseen for several successive weeks, and 
sometimes remains without setting for as long a period, 
while even in the heart of summer a cold more intense 
than our bitterest winters prevails, how startling would be 
the thought (familiar though it now seems to us) that there 
are not only living creatures in the Arctic regions, but 
that a race of men exists and thrives there, even preferring 
their strange abode to the temperate regions which seem 
to us so much more pleasant ! 

It is remarkable, indeed, that while our lips are ready 
to speak of the goodness of Grod to all His creatures, and 



52 The Expanse of Heaven. 

of His infinite wisdom and power, we very often treat the 
question of life in other worlds as though the Almighty's 
power and wisdom were limited, and as though He would 
cause other worlds to be inhabited not by creatures suited 
to the conditions prevailing in those worlds, but by 
creatures such as we are familiar with, although such 
creatures would certainly be most miserable, if they could 
exist at all, in any world but ours. May it not justly be 
said in answer to such reasoning, < Oh that Grod would 
speak, and open His lips, and that He would show the 
secrets of wisdom, that they are double to that which is ! 
Canst thou by searching find out God ? canst thou find 
out the Almighty unto perfection ? It is as high as 
heaven ; what canst thou do ? Deeper than hell ; what 
canst thou know ? The measure thereof is longer than 
the earth, and broader than the sea.' 

There is another circumstance in the condition of 
Venus which, according to our ideas, seems inconsistent 
with the well-being of her inhabitants, but may never- 
theless be recognised by reasoning beings on Venus as 
affording excellent illustrations of the beneficence of the 
Almighty. I refer to the slope of her axis to the path in 
which she travels. It is known, of course, to my readers 
that it is the slope or tilt of the earth's axis which occa- 
sions the changing seasons of our earth, and they doubtless 
remember the striking descriptive passage in Milton's 
< Paradise Lost ' — 



The Evening Star. 53 

Some say, He bid His angels turn askance 
The poles of Earth twice ten degrees and more 
From the Sun's axle ; they with labour push'd 
Oblique the centric globe. Some say, the Sun 
Was bid turn reins from th' equinoctial road, 
Like distant breadth to Taurus with the seven 
Atlantic Sisters, and the Spartan Twins, 
Up to the Tropic Crab ; thence down amain 
By Leo, and the Virgin, and the Scales, 
As deep as Capricorn, to bring in change 
Of seasons to each clime; else had the spring 
Perpetual smiled on earth with vernant flow'rs, 
Equal in days and nights. 

But in Venus, if the observations of certain telesco- 
pists can be relied on, the poles are ' turned askance ' two 
score degrees and more ; and thus all the seasons are 
exaggerated : or rather, there results a state of things 
differing in all respects from our terrestrial seasons. 
This would not be the proper place to discuss the effects 
actually resulting in different parts of Venus (and, besides, 
I have already given a full account of those effects in my 
4 Orbs Around Us ') ; but one single case corresponding to 
that of our own country on the earth will serve to show 
how very strangely the seasons progress in Venus. We 
know that here in London the sun at noon in spring and 
autumn rises about 38 J degrees above the horizon (the 
point overhead is 90 degrees from the horizon). But in 
summer he rises higher, ' twice ten degrees and more,' or 
in fact to a height of about 62 degrees, at noon ; while in 
winter he is as much lower at noon, and so attains only 
a height of about 15 degrees. Everyone knows, too, how 



54 The. Expanse of Heaven. 

much longer the day is in summer than in winter. 
Hence we have the pinching cold and scorching heat of our 
extreme winter and summer. But in Venus, at a place 
in the same latitude as London on earth, a much more 
remarkable change must take place. For there, as here 
in London, the sun at noon in spring or autumn must be 
about 38^ degrees above the horizon ; but at noon in 
midsummer he is almost exactly overhead (in point of 
fact more than 90 degrees from the southern horizon — 
that is, he is rather on the northern side of the point 
overhead). At noon in midwinter he is not seen at all ; 
for the slope of Venus's axis amounts to more than 50 
degrees, and therefore the winter noonday sun is depressed 
more than 50 degrees below the place of the spring or 
autumn noonday sun, which, as we have seen, is but 38^ 
degrees above the horizon. In winter, then, in a place 
situated on Venus as London is on the earth, there is no 
day. And it is easily seen that there is no night in 
summer. In fact, such a place presents the same pecu- 
liarity in this respect which is observed within our Arctic 
and Antarctic regions. But it also resembles places within 
our torrid zones, in having the noonday sun overhead in 
summer. When it is added that the change from the 
extremely hot summer (with a sun twice as large as our 
own overhead at noon, and still high above the horizon at 
nominal midnight) to the bitter cold of winter (with the 
sun far below the horizon at nominal noon) takes place in 
less than four of our months, it will be seen that if there 



The Evening Star. 55 

is a London on Venus the Londoners there must be of 
singularly strong constitutions. It is thought a trying 
change for the ordinary Londoner to visit the hotter 
regions of the tropical zone; and it is an even more 
trying change for him to penetrate within the Arctic 
regions. But to have a summer more than twice as hot 
as our hottest torrid weather, a cold as extreme as that of 
our Arctic winters, succeeding each other at intervals of 
four months, would certainly kill in a year or two not 
merely the ordinary Londoner, but the hardiest specimen 
of the hardiest races of mankind. But assuredly 6 Touch- 
ing the Almighty we cannot find Him out ; He is excellent 
in power and in judgment, and in plenteousness of justice; 
He will not afflict.' 



56 The Expanse of Heaven. 



THE RUDDY PLANET. 

The snows that glittered on the disc of Mars 

Have melted, and the planet's fiery orb 

Bolls in the crimson summer of its year. — Holmes. 

Duking May there shines in the south a ruddy orb which 
can scarcely be mistaken for a fixed star. It is the 
planet Mars pursuing his course (now retrograde) through 
the constellation of the Virgin. In this constellation 
there is but one star which is comparable in brilliancy 
with the planet Mars — the star Spica Azimech, which 
marks the ear of corn carried in the maiden's hand ; and 
the eye recognises at once a marked difference between 
the sparkling light of the star and the steady glow of the 
ruddy planet. It may in passing be noticed that a fine 
opportunity is afforded the young astronomer of observing 
the chief distinction between a planet and a fixed star. It 
is quite commonly imagined that only long and patient 
watching can reveal the movements which are charac- 
teristic of the planets (and whence, indeed, they derive 
their name, since the word planet signifies c a wanderer '). 
But even in a few hours Mars perceptibly changes his 
place among the fixed stars ; and if he be watched 
night after night during a favourable opportunity — 



The Ruddy Planet. 5 7 

let us say from the end of May until the end of June 
— he will be seen to traverse a very considerable portion 
of one of the great loops in which he circuits the 
zodiac. I can imagine few more instructive or sug- 
gestive exercises than thus to track a planet which, like 
Mars, or Jupiter, or Saturn, is conspicuous from time to 
time in our night skies as distinguished from the twi- 
light skies on which the planet Venus pursues her course. 
The task is not at all a difficult one. All that is necessary 
is to prick down on a sheet of white paper the stars of the 
constellation which the planet is traversing. The ordi- 
nary almanacs tell us which constellation this chances to 
be, and any good star-atlas will give the conspicuous 
stars. 

Then each night the young astronomer should notice 
where the planet is situated among these stars, and 
should jot down its place accordingly in his star-sheet. 
When a few days have passed he will begin to recognise 
the nature of the track which the planet is pursuing, 
and he will have pursued himself a portion of the track 
by which the earliest astronomers were gradually led to 
the knowledge of the true arrangement of that wonderful 
scheme of orbs over which the sun bears sway. Nay, if 
the planet he has selected has been Mars — now the best 
placed by far for the purpose, and always remarkable 
when so placed for the rapidity of his motions — the 
young astronomer will have been repeating, in a rough 
way, the observations which led Kepler to the knowledge 



58 The Expanse of Heaven. 

of those laws on which Newton based the whole system of 
modern astronomy. 

It appears to me that the study of the heavens is not 
less instructive in this aspect than in the wonderful facts 
which it has revealed. I find, indeed, a special • charm in 
the contemplation of the great problems of astronomy as 
they presented themselves to men before the time had 
come when the great secret of the universe was to be 
revealed. There is much in the thoughts suggested by 
such contemplation to afford encouragement on the one 
hand, and to teach modesty on the other. If we feel 
gratification, and some degree of pride in the intellectual 
powers given to man, when we consider the marvellous 
way in which the truth in these matters has been attained, 
we must nevertheless perceive how prone man is to error, 
when we recall how for century after century a false 
system of astronomy was complacently taught at all the 
great seats of learning. 

There is another excellent reason for studying the actual 
motions of the celestial bodies when favourable oppor- 
tunity occurs. This reason is that set forth by Milton, 
when he makes the archangel say to Adam : — 

To ask or search I "blame thee not ; for Heaven 
Is as the book of God before thee set, 
Wherein to read His wondrous works, and learn 
His seasons, hours or days or months or years. 

And no other subject of observation is pleasanter or more 



The Rtcddy Planet. 59 

instructive than the movement of the planets, as they 
pursue 

Their wand'ring course, — now high, now low, then hid, 
Progressive, retrograde, or standing still. 

Let us pass, however, to the consideration of the 
planet Mars as exhibited to us by the teachings of 
astronomy. 

We note, then, first, that Mars is strikingly contrasted 
to the two planets hitherto considered — Venus and Jupiter 
— unlike though these two planets are to each other. 
' One star differeth from another star in glory.' We may, 
indeed, almost say that in the whole heavens there are 
not two orbs which resemble each other. In consider- 
ing Venus we were struck by the great amount of light 
and heat which she receives from the sun. With Mars 
all this is reversed. For whereas Venus is the planet 
which travels next to the earth on the inside, or towards 
the sun, Mars travels next to the earth on the outside, or 
away from the sun. Accordingly he receives much less 
light and heat than the earth ; his actual supply (con- 
sidering mile per mile of surface) varies from one-half to 
one-third of the earth's supply, this great variation being 
due to the eccentric nature of the path on which he 
travels. Thus, while Venus receives twice as much light 
and heat as the earth, Mars never receives more than half 
as much as the earth, or one-fourth of the supply afforded 
to Venus. Mars also differs remarkably from Venus and 
our earth in size, and it is in this respect that he affords 



6o The Expanse of Heaven. 

the most remarkable contrast to the planet Jupiter. For 
we have seen that Jupiter is very much larger than the 
earth ? exceeding her more than twelve hundred times in 
volume, and more than three hundred times in mass or 
quantity of matter. Now Mars is very much smaller than 
the earth, being, indeed, much nearer to the moon both 
in point of size and in point of mass. In size he is about 
one-sixth part of the earth ; in mass he is about one-ninth 
part. He is, in fact, the smallest of all the planets except 
Mercury (and of course the members of the ring of small 
bodies travelling between Jupiter and Mars). Moreover, 
he is contrasted to Jupiter in the fact that he has no 
moon, whereas Jupiter, as we have seen, is surrounded by 
a noble family of moons. What renders the contrast 
between these planets more remarkable is that they are 
next neighbours in the solar system, so far as the primary 
planets are concerned. According to the astronomy of 
Newton's day, and until the present century, there were 
in order the planets Mercury, Venus, the Earth, Mars, 
Jupiter, and Saturn ; and thus, next to the two giants 
Jupiter and Saturn, but nearest of all to the greater giant 
Jupiter, there came the least of all the planets except 
Mercury. 

But although Mars is a small and seemingly insignifi- 
cant member of the solar family, he is in reality by no means 
the least interesting of the planets. He is, indeed, the 
one about which we know most. Venus comes nearer to 
us, but when she is nearest we cannot see her, since she 



The Ruddy Planet. 6 1 

then lies directly towards the sun. Jupiter, again, looks 
larger than Mars, and we seem at first sight to perceive 
more in the belted globe of the giant planet than in the 
small red disc of Mars. But all the processes at work in 
Jupiter are seen under the diminishing effect of a distance 
of some 360 millions of miles, whereas Mars, when 
favourably placed, is but some 50 millions of miles from 
us, on the average, and sometimes when he approaches 
at his very nearest, he is less than 40 millions of miles 
from us. 

Under the telescope Mars presents appearances some- 
what like those which we may imagine that our earth 
presents as seen from Venus or Mercury. There are 
reddish tracts which we may regard as the continents of 
the planet, and there are greenish regions which may very 
well be oceans. Assuming this to be the case, we can note 
at once a marked difference between the arrangement 
of land and water in Mars and in our own earth. Our 
oceans exceed the continents nearly three times in extent. 
On Mars land and water are about equally divided. 
Again, the arrangement of land and water on our earth is 
such that in reality the continents may be looked upon as 
great islands. The two Americas form one great island. 
Europe, Asia, and Africa another ; Australia a third ; and 
then there are a multitude of smaller islands. In Mars a 
very different arrangement prevails. The relation is not 
absolutely reversed — that is to say, the oceans in Mars 
cannot be regarded as great lakes ; but an intermediate 



62 The Expanse of Heaven. 

arrangement prevails, land and water being so intermixed 
that the great continents are connected with each other, 
as well as the great oceans. There are of course some 
islands and some lakes, but the chief divisions of land and 
water are connected as described. 1 

The next feature of Mars which has to be noticed is 
the presence of two white patches around the poles of the 
planet. These have long been regarded, and very reason- 
ably, as the Arctic and Antarctic snows and ice fields of 
Mars. It occurred to Sir W. Herschel to study their ap- 
pearance in order to see whether, as the Martial year pro- 
gressed, they changed in size, waxing larger in winter and 
waning again in summer. For Mars has seasons as our 
earth has, his polar axis being sloped to the level of the 
path in which he travels, much as the earth's axis is 
sloped to the level of her path. The slope is rather greater, 
and therefore the seasonal changes must be somewhat more 
marked, but the difference is not very great. It follows 
that during the progress of the Martial year, which lasts 
687 days, there must be spring and summer and autumn 
and winter in one hemisphere of Mars while in the other 
there are the seasons autumn, winter, spring, and summer. 
Now Herschel found, as he expected, that with the pro- 
gress of these seasons the polar snows of Mars wax and 

1 A coloured chart of Mars on the Stereographic projection is given in 
1 Other Worlds/ and a chart on Mercator s Projection in 'Orbs Around Us/ 
'J>om these charts globes of the planet have been formed by Mr. Browning, 
the optician, and by Captain Busk (in the latter case Messrs. Malby have 
made tho globes). 



The Ruddy Planet. 63 

wane much as happens with the snow and ice in our own 
Arctic and Antarctic regions. 

But even more like what takes place on our earth is 
the apparent formation of great masses of cloud, hiding 
from view the Martial lands and seas, sometimes for many 
successive hours. Indeed, it would seem that in the 
winter season of Mars the sky is commonly overcast, x fot 
the features of the winter half of the planet are not 
nearly so well seen as those of the half where summer is 
in progress. And then again it would seem as though at 
early morning and again in the evening fogs and mist 
prevail in Mars, for the parts of the planet which have 
lately come into sunlight, as well as those which are 
about to pass away to the night half of the globe, always 
show a whitish light which altogether conceals the features 
of land and water. 

Perhaps, however, the most remarkable circumstance . 
of all in connection with the ruddy planet is the fact that 
astronomers have been able to prove that there is water 
on Mars. The mere appearance of greenish tracts on the 
planet may suggest the idea that water exists there ; but 
yet we could not be at all sure that this is the case. 
Again, the white polar caps of Mars are very well explained 
by the supposition that they are snow-covered regions ; 
yet this supposition might be altogether erroneous. And 
it might seem as though nothing short of a visit to Mars 
could place the existence of water on the planet's surf^ci# 
altogether beyond dispute. But by means of the wonder- 



64 The Expanse of Heaven. 

ful powers of the new instrument of research called the 
spectroscope, it has been proved beyond all possibility of 
question that there is water on Mars. The way in which 
this has been done is in reality sufficiently simple, though 
it would not be easy to explain it fully in these columns. 
This much, however, may be said in the way of explanation. 
When the sun's light is examined with a spectroscope, the 
white sunlight is changed into a rainbow-tinted streak 
crossed by a multitude of dark lines. When the sun is 
low down, so that his light traverses the lower parts of the 
air, certain new dark lines and bands are seen in the rain- 
bow-tinted streak called the solar spectrum ; and it has 
been proved that some of these new lines are solely due 
to the vapour of water in our atmosphere. Now, the 
light of Mars is reflected sunlight ; and therefore when 
examined with the spectroscope, it gives the rainbow- 
tinted streak and the dark lines which form the solar 
spectrum. But also it gives the dark bands known to 
belong to the vapour of water ; and these bands are seen 
when Mars is high above our horizon, so that the bands 
cannot be due to the vapour of water in our atmosphere. 
Hence it follows that there is the vapour of water in the 
atmosphere of Mars. This vapour can only be raised (in 
sufficient quantities) from the surface of seas and oceans ; 
hence we can infer safely that the greenish tracts are 
oceanic. And it is clear that, having moisture in the 
Martial air, we should expect cloud, rain, and snow — 



The Rttddy Planet 65 

precisely in accordance with the planet's telescopic 
appearance. 

f We appear, then, to have many remarkable indications 
of resemblance between Mars and our own earth. And 
it might appear a natural conclusion to this chapter to 
assert that Mars is, in fact, a miniature of our own earth, 
and in all probability inhabited by such creatures as we 
are familiar with. In another chapter, in which the 
subject will be completed, it will be seen whether this 
conclusion is to be accepted, or whether Mars, like Venus, 
affords evidence of the wonderful diversity of conditions 
which exists throughout the universe of God. 



66 The Expanse of Heaven. 



LIFE IN THE RUDDY PLANET. 

He looketh to the ends of the earth, and seeth under the whole heaven ; 
to make the weight for the winds, and He weigheth the waters by measure. 
— Job xxviii. 24, 25. 

When I was considering the planet Venus, and noting 
those circumstances in her condition which differ in the 
most marked manner from the corresponding circum- 
stances in the case of the earth, I took occasion to point 
out that the Almighty has doubtless so provided for 
creatures living in Venus that the conditions which seem 
to us unfavourable are in perfect accordance with the 
requirements of the inhabitants of that planet. I might 
follow the same course in the case of Mars ; but it appears 
to me that it will be well to take another view of the 
matter. I shall therefore invite the special attention of 
my readers to the unfitness of Mars to be the abode of 
such creatures, animal and vegetable, as exist upon our 
earth. In other words, I shall endeavour to show how 
admirably adapted the earth is to the wants of her 
inhabitants ; for, in reality, this is the lesson to be 
learned from the unfitness of her nearest neighbours, 
Mars and Venus, to be the residence of terrestrial 
races. The reader will not forget, however, that all 



Life in the Rtcddy Planet. 67 

which I shall thus urge must be interpreted in the way 
thus indicated ; he must carefully bear in mind that the 
very circumstances of the condition of Mars, which I am 
to insist upon as unfavourable for terrestrial beings, are 
in all probability those which reasoning beings on Mars, 
if such exist, have the greatest reason for regarding as 
proofs of the beneficence of the Almighty towards the 
creatures inhabiting that planet. 

I pass over for the moment the small supply of light 
and heat received by Mars, because the actual effect of 
the solar rays must depend partly on the nature and 
extent of the Martial atmosphere, which are not certainly 
known, I wish at present to deal only with known facts 
respecting Mars, so as to have nothing uncertain in this 
portion of my reasoning. 

I take first, then, the length of the Martial year. 
Mars requires very nearly 687 days to complete the circuit 
of his path round the sun. In other words, his year 
exceeds ours by 322 days. If we imagine this year of 
Mars divided like ours into twelve months, each of these 
months would contain 57 or 58 days. Now, it is an 
interesting and significant circumstance that the consti- 
tution of the greater number of our vegetables, plants, 
&c, is specially adjusted to the length of our year. If 
our year were suddenly lengthened, even by but a single 
month, the vegetable world would be altogether dis- 
ordered ; ' the functions of plants, 5 as Whewell has said, 

'would be entirely deranged, and the whole vegetable 
4 



68 The Expanse of Heaven. 

kingdom involved in instant decay and rapid extinction.' 
It would be easy, though it would occupy a considerable 
amount of space, to show this by a multitude of instances. 
But I shall content myself with touching on an interest- 
ing circumstance in the natural history of plants, to 
which Linnaeus was the first to call special attention. I 
refer to the fact that plants have each a special season for 
their various functions. Thus, 6 if we consider the time 
of putting on leaves, the honeysuckle protrudes them in 
the month of January ; the gooseberry, currant, and elder 
in the end of February or beginning of March ; the 
willow, elm, and lime-tree in April ; the oak and ash, 
which are always the latest among trees, in the beginning, 
or towards the middle, of May. In the same manner the 
flowering has its regular time : the mezereon and snow- 
drop push forth their flowers in February ; the primrose 
in the month of March ; the cowslip in April ; the great 
mass of plants in May and June ; many in July, August, 
and September ; some not till the month of October, as 
the meadow saffron ; and some not till the approach and 
arrival of winter, as the laurustinus and arbutus.' A 
complete series of such instances would form what has 
been poetically termed a c Calendar of Flora.' 

The different plants require the same portion of time 
for the competition of their several changes, although 
each has its special time of year for throwing out leaves, 
flowering, budding, and so on. It is clear, then, that any 
considerable change in the length of the year would be 



Life in the Ritddy Planet. 69 

fatal to vegetable life. The first year of the new kind 
would be perhaps merely a year of confusion. As 
Whewell well remarks, ' What would become of the ca- 
lendar of Flora if the year were lengthened or shortened 
by six months ? ' But the second year, or the third at 
latest, would bring about the destruction of nearly all the 
orders of plants now existing on our earth. 

Whatever, then, may be the state of Mars as respects 
animal life, it is quite certain that all forms of vegetable 
life in Mars are unlike those existing on our earth. We 
may take it for granted that there is not a single plant 
now living in Mars which would thrive or even exist if it 
could be removed to our own earth. 

The day in Mars differs so little in length from our 
own day, that it would be difficult to show that either 
animal or vegetable life in Mars would differ much on 
this account alone from such life on our earth. The 
Martial day exceeds our own by a little more than half 
an hour. Thus what has been called the Dial of Flora, 
or Flower-clock, in which the opening and closing of 
flowers mark the several hours, would be put very little 
out of order if our day changed to the Martial day. 
Probably nearly all flowers would adapt themselves readily 
enough to the change ; though it is to be noticed that 
Whewell, 1 after a careful consideration of the evidence, 

1 All that I quote from Whewell in the present paper has been taken 
from his * Bridgewater Treatise on Astronomy,' not from his book on the 
• Plurality of Worlds/ 



Jo The Expanse of Heaven. 

arrives at the conclusion that 6 the power of accommoda- 
tion which vegetables possess in this respect is far from 
being such as either to leave the existence of the periodi- 
cal constitution doubtful, or to entitle us to suppose that 
the day might be considerably lengthened or shortened 
without injury to the vegetable kingdom.' 

But we come next to a feature of very great importance 
in the economy of Mars, the attraction of gravity at his 
surface. The reader is aware that the attraction of 
gravity at the earth's surface depends on the quantity of 
matter in the earth, and also on the size of the earth. 
If the earth contained as much matter as at present, but 
had a diameter only half as great as at present, gravity 
would be four times as great as it is now ; in other words, 
everything on the earth would weigh four times as much. 
But if the earth were of the same size as at present, but- 
contained more or less matter, the attraction of gravity 
would be correspondingly increased or diminished. Now, 
in the case of Mars we find a very much smaller quantity 
of matter, as I mentioned in my last; and if we only 
considered this difference, we should infer that gravity 
was only one-ninth as great at the surface of Mars as at 
the earth's surface. But the diameter of Mars is less 
than the earth's in the proportion of about 1 1 to 20 ; and 
this tends to increase gravity in the proportion of 20 
times 20 to 11 times 11 — that is, as 400 to 121, or about 
10 to 3. Now, if we first decrease our terrestrial gravity 
to one-ninth its value, and then increase the result as 10 



Life in the Ruddy Planet. 7; 

to 3, we get finally a decrease in the proportion of 10 to 
27. This shows that a body which would weigh 27 
pounds on the earth would, if removed to Mars, weigh 
only 10 pounds; using the word ' weigh' to mean the 
actual pressure downwards, for of course in the ordinary 
way of measuring weights by a balance there would be no 
difference. 

Now, this difference in the downward pressure of all 
objects on Mars, as compared with terrestrial objects of 
equal mass, would produce results . of a veiy mischievous 
nature if it were suddenly to be extended to our earth. In 
the first place, the mere change in the weight of all 
objects, including the bodies and limbs of animals, would 
lead to a variety of unpleasant results. Whewell remarks 
that in such a case i we should discover the want of the 
usual force of gravity by the instability of all about us. 
Things would not lie where we placed them, but would 
slide away with the slightest push. We should have a 
difficulty in standing or walking, something like what we 
have on shipboard when the deck is inclined; and we 
should stagger helplessly through an atmosphere thinner 
than that which oppresses the respiration of the traveller 
on the tops of the highest mountains.' And he very well 
notes that all this shows the real importance of those 
dark and unknown central portions of the earth which we 
are apt to regard as c deposits of useless lumber without 
effect or purpose. We feel their influence on every step 
we take and on every breath we draw ; and the powers we 



72 The Expanse of Heaven. 

possess, and the comforts we enjoy, would be unprofitable 
to us if they had not been prepared with reference to those 
as well as to the near and visible portions of the earth's 
mass.' 

Another instance of the importance of the actual 
value of the force of gravity is found in the correspon- 
dence between the force with which the sap of plants is 
impelled upwards, and the downward action of gravity 
restraining this upflow. It may, perhaps, be thought at 
first by many readers that the upward force producing the 
flow of sap is but slight, since this flow is so gentle a 
process ; but it will suffice to mention the experiments of 
Hales to show that this is not the case. He found, for 
instance, 'that a vine in what is called the bleeding 
season can push up its sap in a glass tube to a height 
of twenty-one feet above the stump of an amputated 
branch.' It is clear that any considerable change in the 
force of gravity would be most injurious to plant life. 
An increase of gravity would cause the activity of the 
vegetable circulation to be greatly reduced ; an increase of 
gravity would unduly hasten the rising of the sap, ' and 
probably hurry and overload the leaves and other organs, 
so as to interfere with their due operation.' 

Another illustration, and a very beautiful one, is 
pointed out by Whewell in the positions of flowers. ' Some 
flowers grow with the hollow of their cup upwards ; others 
"hang the pensive head" and turn the opening down- 
wards.' It is obvious that an increase of gravity would 



Life in the Ruddy Planet 73 

force the upright plants to hang their heads, while a 
decrease to the value of gravity which actually exists in 
Mars would cause the drooping heads to stand erect. But 
it has been shown by Linnseus that on the position of the 
heads of flowers, combined with the greater or less length 
of the pistil and stamens, depends the fertility of the 
plant. So that, as Whewell remarks, ' the whole mass of 
the earth, from pole to pole, and from circumference to 
centre, is employed in keeping a snowdrop in the position 
most suited to the promotion of its vegetable health.' 

But the most important effect of all is that which 
would be produced on the atmosphere. If gravity were 
reduced to precisely the value it has in Mars, our air would 
immediately be released from more than half the coercive 
force now drawing it downwards to the earth. It would 
still be drawn downwards, but so much less that the density 
of the air at the sea-level would be reduced in the same 
degree as gravity — that is, in the proportion of 10 to 27. 
The mercurial barometer would, in fact, stand at about 1 1 
inches instead of 30. This corresponds to the effect which 
takes place in an elevation of about five miles. Now, there 
are no creatures but certain races of birds which exist on 
our earth at this enormous elevation, and probably very 
few races of terrestrial animals could survive the change 
to so rare an atmosphere. 

Now we are indeed here touching upon a somewhat 
doubtful feature of the condition of Mars, whereas I have 
set myself as a law in the present essay the avoidance of 



74 The Expanse of Heaven. 

all doubtful points. We do not know whether there is 
more or less air around Mars than around our earth ; 
but nevertheless we can be quite certain that in one way 
or another a state of things must exist which would be very 
unfavourable to the creatures living on our earth. If on 
the one hand ; the quantity of air is so much greater in 
Mars that the actual density of the air at the sea-level is 
the same as with us, then this air, when moving in winds 
and storms, must be much more effective in overthrowing 
objects like our terrestrial animals and vegetables, simply 
because they are so much less strongly kept in their place, 
in consequence of the feeble gravity of Mars. Besides, if 
the air is no denser on Mars than with us,' there must 
prevail an intense cold, in consequence of the greater dis- 
tance of Mars from the sun ; and if we have a denser air, 
the Martial hurricanes become still more destructive. On 
the other hand, if the Martial air is rarer than ours, the 
cold is still more intense, and thus the condition of Mars 
is seen to be on this account altogether unfit for such 
creatures as exist upon our earth. 

We see, then, that for many distinct reasons Mars 
cannot be the abode of living creatures resembling those 
with which we are familiar. And we learn to recognise 
the loving care with which the requirements of terrestrial 
creatures have been adapted to the circumstances under 
which they subsist, when we note that even in Mars, the 
planet which, perhaps, on the whole most nearly re- 
sembles our earth, all forms of terrestrial life would quickly 
perish. 



TEE PRINCE OF PLANETS. 

He made darkness pavilions round about Him, dark waters, and thick 
elouds of the skies. Through the brightness before Him were coals of fire 
kindled. — 2 Samuel xxii. 12, 13. 

On any evening during the month of April there can be 
seen, towards the south, a star far brighter than any other 
in the heavens, except (for a part of the time) the evening 
star towards the west. The star in the south is the 
mighty Jupiter, the leader of all the planets, exceeding 
all the rest together as well in volume as in mass, and so 
far surpassing our earth in these respects that he may 
fairly be regarded as a body serving an altogether different 
purpose in the scheme of creation. I propose to give a 
brief account of this wonderful globe, pointing out in 
particular the circumstances which distinguish him from 
this earth on which we live. 

But first let us consider the wonderful contrast 
between the aspect of this planet as seen by the unaided 
eye and his real condition as revealed to us by the tele- 
scope, Eegarding him as he shines on a dark and clear 
night, we seem to see a bright but small object. Com- 
pared with the moon, for instance, Jupiter seems little 
more than a point of light. Then, watching him from 



76 The Expanse of Heaven. 

hour to hour, we observe that he appears to be at rest 
among the stars, though sharing with them in the motion 
by which all the orbs of heaven are apparently carried 
from east to west in consequence of the earth's rotation 
upon her axis. To the untutored mind Jupiter presents 
no single feature teaching his real nature and his im- 
portance in the creation. 

And now, in turn, let us consider what astronomy tells 
us respecting him. 

That small but brilliant orb is a globe so large that, 
compared with it, our earth is no larger than a pea com- 
pared with an orange. Twelve hundred and thirty orbs 
as large as our earth would be required to form such a 
globe as Jupiter's. In mass he does not exceed our earth 
so greatly ; but still it would require the mass of three 
hundred earths to make up Jupiter's. That star which 
seems to us a point compared with our moon, is attended 
on by four orbs, the least of which is as large as our moon, 
while the others are larger than the moon, one being as 
large as the planet Mercury. 

But even more wonderful is the thought of the enor- 
mous rate of motion with which that vast orb is being- 
carried along with its attendant family through space. 
In each second Jupiter's giant bulk moves eight miles, 
a rate exceeding about five hundred times the velocity of 
the swiftest express train. I have said that his attendant 
family is carried along with him. But besides this motion 
which they share with him, these orbs (which no eye 



The Prince of Planets. 7 7 

perceives without telescopic aid, so completely are they 
lost in the glorious light of their ruling planet) are them- 
selves travelling around Jupiter with motions of enormous 
rapidity. Nay, the nearest moon travels even faster on its 
course round Jupiter than Jupiter travels on his course 
round the sun. It moves no less than eleven miles per 
second ; so that at one part of its course, when its motion 
conspires with Jupiter's, it is advancing nineteen miles 
per second, while at the opposite part of its course it is 
moving backwards at the rate of three miles per second. 
The other moons have corresponding varieties of motions ; 
and yet these enormous and complex movements are not 
merely rendered undiscernible by vastness of distance, but 
the orbs which take part in them are actually invisible 
until the giant eye of the telescope reveals them to us. 

When we know that Jupiter is an orb so mighty, and 
the centre of a scheme so remarkable, the thought is 
naturally suggested that he must be the abode of living 
creatures. It is almost impossible for us to conceive any 
other purpose for which so noble a planet can have been 
framed. And let the unbeliever sneer as he will, the 
thoughtful mind will recognise in such a consideration a 
valid argument. It is true that men have repeatedly 
erred when they have attempted to reason from their 
limited conceptions of the purposes of the Almighty ; and 
it would be incorrect to argue that Jupiter is an inhabited 
world because the earth is inhabited, and therefore the 
planets are apparently intended to be inhabited. But if 



yS The Expanse of Heaven. 

it could be shown that the only purpose which Jupiter 
could possibly subserve was that of supplying an abode 
for living creatures, this would form a very strong argu- 
ment to most persons, and an irresistible argument to 
many, in favour of the opinion that Jupiter actually is 
inhabited. 

And yet when we consider the circumstances under 
which this giant planet exists, we can scarcely suppose 
that there are living creatures on its surface. There is, 
in the first place, its enormous distance from the sun, 
whereby the light and heat received at Jupiter is reduced 
to less than the twenty-fifth part of that which we receive. 
It is no doubt true that the actual climate of the planet 
may depend much on the nature of the Jovian atmosphere ; 
for we see that at the summits of high mountains on the 
earth, even in tropical regions, a cold so intense prevails 
that snow perpetually clothes the mountain peaks. But an 
atmosphere can after all only as it were garner up the heat 
that it receives ; it cannot increase the quantity received. 
And so far as we know, the only way in which any atmo- 
sphere such as we could live in could thus store up the 
heat received, is by the action of the vapour of water. 
But it may be doubted whether the sun's direct heat on 
Jupiter could be capable of causing the water on Jupiter 
to evaporate to any considerable extent. It is the sun's 
heat which loads our air with the vapour of water, and 
then this vapour (especially at night) prevents the heat 
from escaping so rapidly as it otherwise would. But the 



The Prince of Planets. 79 

feeble sun of the Jovian sky could hardly raise any water 
vapour into his atmosphere. 

Let us, however, enquire what the telescope tells us 
about the atmosphere of Jupiter. It is clear that we 
might expect to find the signs of a great stillness in that 
atmosphere, if the sun's action alone ^effected it. For we 
know that all the disturbances of our own air are due to 
the sun's heat ; wind and cloud, storm and rain, are alike 
generated by his action. So that where his direct action 
is so much less as it must needs be in the case of Jupiter, 
we might expect an unchanging aspect to be presented. 
But the reality is very different. Examined by a power- 
ful telescope, Jupiter shows all the signs of the most 
tremendous atmospheric disturbances. There are great 
bands of clouds all around him, so arranged as to imply 
the existence of very strong winds resembling our trade 
winds. But these cloud zones change sometimes so 
rapidly in shape as to show that either some of the clouds 
have rapidly discharged their contents in rain and new 
clouds have been very rapidly formed, or else that great 
cloud-masses have been carried along with enormous 
rapidity by winds of hurricane force. In some cases it 
has been difficult to determine which of these events has 
taken place, but in others it has been manifest that tre- 
mendous storms must have occurred. In passing, indeed, 
I may remark that it matters very little so far as the main 
argument is concerned whether we take one view or the 
other ; since it is clear that the formation and dissipation 



80 The Expanse of Heaven. 

of cloud-masses over enormous regions (regions in many 
cases exceeding the whole surface of our earth in extent) 
must indicate forces of great activity in Jupiter, quite 
as satisfactorily as the existence of violent hurricanes. 
Nevertheless, the mind is more prone to recognise the 
activity of those forces which occasion actual movement 
than that of the silent but most energetic forces which 
produce or dissipate great cloud-masses. Now, there have 
been cases where it has been manifest that the most 
tremendous hurricanes must have agitated the atmosphere 
of Jupiter. For it has been possible to watch the gradual 
motion of cloud-masses on Jupiter, and thence to deter- 
mine the rate of the wind which carried them, as certainly 
as one can tell the rate at which a terrestrial cloud is 
moving by noting the rate of motion of its shadow. And 
these gradual motions of cloud-masses on Jupiter, when 
interpreted by what we know of the real dimensions 
of Jupiter, have been found to indicate the existence 
of winds blowing at the rate of nearly 200 miles per 
hour. 

The most remarkable circumstance about these Jovian 
hurricanes remains to be mentioned, however. Our ter- 
restrial storms rage sometimes for five or six days in 
succession, but this is very unusual. Ordinarily the 
fiercest storm blows itself out in less than three days. 
Now, Jovian hurricanes have been known to last for six or 
seven weeks. When this circumstance is considered in 
connection with the rate at which these storms blow, it is 



The Prince of Planets. 8 1 

impossible to resist the impression that Jupiter is little 
suited to be the abode of living creatures. 

Sir John Herschel states, in his treatise on Meteorology, 
that a wind-storm blowing at the rate of 90 miles per 
second is capable of overturning all but the most strongly- 
built houses and of uprooting the stoutest forest-trees. 
And every mile per second added to the velocity of such a 
storm increases its destructive power in a marked degree. 
Fortunately such storms occur but seldom, are limited in 
their range, and last but a short time. What, then, would 
happen if a storm raged for a couple of months, over a 
region exceeding the whole surface of the earth in extent, 
the velocity of the wind being more than twice as great 
as that of the most tremendous and destructive hurricanes 
known on our earth ? No living creatures known to us 
could survive such a storm; the strongest buildings men 
have erected would be destroyed by it in a few minutes ; 
every region over which it raged would be desolated. 
Yet such storms are not infrequent in Jupiter. 

But, after all, the main inference derivable from these 
hurricanes does not relate to their effects, but to their 
cause. Such hurricanes would doubtless make Jupiter an 
unsuitable abode for men ; yet it is not wholly inconceiv- 
able that creatures more strongly framed and capable of 
building more solid edifices might live comfortably 
enough even where such tornadoes occurred from time to 
time. But when we enquire how these storms can be pro- 
duced, we are led to an opinion which is strongly opposed 



82 The Expanse of Heaven. 

to the idea that Jupiter can be inhabited. It is incredible 
that the feeble sun of Jupiter occasions these storms. 
Wind can only be generated by heat ; and great winds 
are occasioned by great contrasts of temperature. Where 
are we to look for such heat and such contrasts in Jupiter? 
Since we cannot ascribe these effects to the sun, we are 
forced, I think, to regard them as due to some cause 
inherent in the planet itself. It would seem as though an 
intense heat must prevail in Jupiter's substance, and that 
to this heat not only the Jovian hurricanes but the Jovian 
cloud-bands themselves must be ascribed. To speak 
plainly, it would seem as though Jupiter were so tre- 
mendously hot that the waters on his surface continually 
throw up vast masses of water-vapour — nay, when we 
remember the enormous quantity of water which must be 
present in his cloud-bands, it would seem almost certain 
that the whole of those waters which would otherwise 
form oceans on his surface, are converted into steam, 
which in the upper parts of his atmosphere condenses into 
the form of visible water-vapour, or cloud. 

If such is actually the condition of Jupiter, life can 
scarcely exist on his surface. It is, indeed, always 
possible, as I have said in speaking of Venus, that life 
may exist under conditions which to our feeble concep- 
tions appear altogether intolerable. But there is a great 
difference between such conditions as we considered in the 
case of Venus and the state of a globe such as Jupiter 
seems to be. The relations of heat and cold of Venus 



The Prince of Planets. 8 3 

differ only in degree from the relations with which we are 
familiar on earth ; but a globe actually hot enough to 
turn enormous masses of water into steam could only be 
inhabited by creatures incapable of being injured by fire, 
and it is difficult for us to imagine that there can be such 
creatures. 

It would indeed seem as though the actual globe of 
Jupiter were red-hot ; since from time to time, when the 
great white cloud-belt which surrounds his torrid regions 
has been dispersed, a strange fiery hue has been observed 
over this zone, which strongly suggests the idea of a 
glowing central globe. And when the light of Jupiter has 
been measured it has been found to exceed that which 
would be given by a globe of equal size simply reflecting 
the sun's light. 

It would seem, then, that this noble planet, surpassing 
all the other planets together, as well in bulk as in mass, 
is not an inhabited world. We seem forced to the con- 
clusion that his bulk is useless, his mass and might power- 
less for good. We cannot imagine that he was con- 
structed to afford light in the earth, beautiful though he 
may be as a star in our skies ; it is an idle thought, I con- 
ceive, that his noble system was intended merely to afford 
a subject of study to terrestrial astronomers, profoimd 
though the problems are which the movements of his 
moons afford; the solar system does not require for its 
safety the perturbations which the mass of Jupiter 
occasions in the motions of the planets. Yet I propose to 



84 The Expanse of Heaven. 

endeavour, in my next chapter, to show that even to our 
feeble conceptions there is enough in what we know of the 
Prince of Planets to show that he may fulfil purposes such 
as we can understand. For the present I leave the 
questions which I have raised to the consideration of my 
readers, reminding them, however, that even if it could be 
demonstrated that Jupiter serves no purpose conceivable 
by us, it would be unreasonable to conclude that he had 
been made for no useful purpose. For ' behold Grod 
exalteth by His power : who teacheth like Him ? who 
hath enjoined Him His way ? or who can say, Thou hast 
wrought imperfectness ? Eemember that thou magnify 
His work, which men behold. Every man may see it; 
man may behold it afar off. Behold Grod is great, and we 
know Him not.' 



JUPITER S FAMILY OF MOONS. 

Lift up your eyes on high, and behold who hath created these things. 

Isaiah xl. 26. 

We have seen that Jupiter, although the chief planet of 
the solar system, is probably not the abode of any living 
creatures, and is certainly unfitted to be the abode of such 
creatures as we are familiar with. Yet his enormous bulk 
and mass, the noble sweep of his orbit, the importance, 
beauty, and symmetry of the system over which he bears 
sway, all suggest the idea that he was not created in vain. 
Nor can we readily conceive any purpose he can fulfil save 
that of supplying or helping to supply the wants of living 
creatures. In fact, it is in this way that we view 
all the celestial bodies. We are not contented when 
studying the sun, for example, with the mere consideration 
of the wonderful processes taking place upon his surface 
and around him ; but we enquire how these processes are 
related to his power of supplying our wants, and the wants 
of all that live upon the earth, by means of the light and 
heat which he emits. We study our moon in the same 
spirit ; we see that whether she be herself inhabited or 
not, she was not created in vain — she rules our tides, she 



86 The Expanse of Heaven. 

gives us an important though intermitting supply of light 
by night, she serves as a measure of time, she helps to guide 
the seaman over the trackless waves of ocean, and she 
subserves our wants in a variety of other ways. And it 
is the same method of viewing the celestial bodies which 
has led nearly all men to believe in the existence of multi- 
tudes of other worlds than ours. 

Now, when we apply these considerations to Jupiter 
and his system, we find in his moon-family an increase to 
the difficulty which has already engaged our attention. 
For what are those four orbs intended ? If Jupiter is not 
inhabited, they serve none of the requirements which our 
own moon fulfils. If Jupiter is . inhabited, the moons 
still seem to be of little use. For we can see that Jupiter 
has a very dense and vapour-laden atmosphere, and it is 
altogether improbable that any of the moons can be seen 
from his real surface, supposing he has a surface, which is 
very far from being a certainty. But even if we suppose 
that his moons can be seen, they can supply very little 
light during the planet's night. A different opinion has 
long been entertained, owing to the details of the matter 
being left unconsidered. Sir David Brewster, for instance, 
in his pleasant little work called < More Worlds than One,' 
has dwelt upon the moons of Jupiter as obviously fulfilling 
the important purpose of compensating the planet for the 
small amount of light received from the sun; and he 
speaks of the wonderful beauty of the scene presented by 
Jupiter's moons when all visible at once. But if we con- 



Jttpiters Family of Moons. 87 

sider. the actual circumstances under which these moons 
are placed, we shall find that they cannot be even so effec- 
tive as our own single moon in supplying light to their 
primary planet, while we know well that the light of ten 
such moons as ours would be but a poor compensation for 
the loss of twenty-four parts (out of twenty-five) of the 
sun's light and heat. These moons lie at such distances 
from Jupiter, that while the nearest looks considerably 
larger than our moon, 1 all the others look far less. The 
farthest, indeed, must show a disc little more than a 
quarter of our moon's in diameter, and about a fourteenth 
of the moon's disc in apparent size. But of course all 
these moons together cover a considerably larger part of 
the sky (when they are all seen at once) than ever is 
covered by our moon. It might seem, then, that they 
must give much more light. But then it must be remembered 
that they are themselves only illuminated by the same 
small sun which shines in the Jovian skies. Supposing 
them to be constituted like our own moon, the apparent 
brightness of their discs must be about a twenty-fifth part 
only of that of hers. When due account is taken of this 
circumstance, it is found that the full-moon brightness of 



1 At least when nearly overhead ; but owing to the enormous size of 
Jupiter, there is a great difference in the apparent size of his nearest 
moon when high above the horizon and when low down. "When overhead 
this moon is at its nearest, and shows a disc exceeding our moon's by more 
than a fifth part in diameter, and nearly half as large again in apparent 
size. But when near the horizon this moon is very little larger than our 
own. 



88 The Expanse of Heaven. 

the four moons of Jupiter amounts only in all to a six- 
teenth part of the brightness of our full moon. And even 
this is not all. The four moons never can be all full 
together, though they can be all above the horizon at 
the same time. The innermost, which of course looks the 
largest, is always eclipsed by the vast shadow of Jupiter, 
when directly opposite the sun ; so that this moon is never 
seen full. The same applies to the second moon, which is, 
however, eclipsed on a much shorter part of its course. 

It appears, then, that the moons of Jupiter are utterly 
unfit to compensate for the defect of sunlight. 

But before we dismiss the Jovian family as useless 
moons, after already dismissing Jupiter as a useless world 
(speaking always of his adaptation to the wants of creatures 
living upon him), let us enquire whether we may not, by 
reversing the functions of planet and planet-family, obtain 
an explanation of both. Why should not the moons of 
Jupiter be inhabited, instead of Jupiter himself, and 
Jupiter be appointed to compensate them (not they him) 
for the smallness of the direct supply of solar light and 
heat? 

Here we must not be staggered by the great superiority 
of Jupiter in bulk and mass. We must remember 

That great 
Or bright infers not excellence : the earth, 
Though, in comparison of Heaven, so small, 
Nor glist'ring, may of solid good contain 
More plenty than the sun that barren shines, 



J-upiters Family of Moons. 89 

Whose virtue in itself works no effect, 

But in the fruitful earth ; there first received, 

His beams, unactive else, their vigour find. 

Jupiter's relation to his family of four moons does 
indeed resemble in a somewhat marked manner the rela- 
tion of our sun to the four worlds — Mercury, Venus, the 
Earth, and Mars — which travel nearest to the central 
luminary, and are most peculiarly to be regarded as the 
sun's family. Jupiter surpasses each of his moons in bulk 
and mass in a degree corresponding to that in which the 
sun surpasses the four small planets just named (not 
equally, but the disproportion is of the same order). The 
third of his moons is the largest, just as this earth, the 
third of the sun's inner family of four planets, is the 
largest of that family. The other three moons are about 
equal together in mass to the largest, just as Mercury, 
Venus, and Mars are about equal together, in mass, to the 
earth, and the distances at which the moons travel are 
proportioned to each other somewhat like those observed in 
the case of the four small planets. 

We know that the distances of Mercury, Venus, and the 
Earth, and Mars from the sun are fairly represented by the 
numbers 4, 7, 10, and 16; those of Jupiter's family of moons 
are fairly represented by the numbers 4, 6^, 10, and 18, 
which, under the circumstances, indicates a sufficiently close 
resemblance. In particular I would invite the reader to 
notice how complete is the contrast between the positions 
which the moons of Jupiter bear as compared with that 



90 The Expanse of Heaven. 

occupied by our own moon. The largest of Jupiter's 
moons has a mass less than the 110,000th part of Jupiter's; 
our moon, on the contrary, is about equal to the eightieth 
part of the earth. As respects mass, our moon is in fact 
rather to be regarded as the fifth and smallest member of 
the inner family of planets, than as occupying a totally 
inferior position as a body of another order. The earth 
exceeds Mercury very much more, as well in mass as in 
volume, than Mercury exceeds the moon. Jupiter's moons, 
on the other hand, belong as distinctly to an inferior 
order, when compared with him or his fellow giants among 
the planets, as our earth when compared with the sun. 

Now, our difficulties begin to diminish when we regard 
the moons of Jupiter as the abode of life, and Jupiter as 
the ruler of the system, subordinate of course to the sun. 
For we must remember that every one of Jupiter's moons 
is in reality a planet travelling round the sun. Each one 
of them has its year, its day, and probably its seasons. 
For anything, indeed, that is known, the inhabitants of 
each may regard their little world as the centre of the 
universe ; since to a creature placed on one of those 
moons all the circumstances would be presented which 
caused the ancients to regard our earth as the fixed centre 
of created things. Jupiter must appear to them as a 
gigantic moon ; and he really is capable of compensating 
them to a noteworthy extent for the small amount of 
light supplied to them by the sun. Certainly this is the 
case with the nearest moon, since Jupiter must show a 



Jupiter y s Family of Moons. 9 1 

disc exceeding our moon's more than fourteen hundred 
times in apparent surface, and supplying more than fifteen 
hundred times as much light as our fall moon. Even in 
the case of the outermost moon the apparent surface 
of Jupiter's disc must exceed that of our moon about 
sixty-five times, and supply about eight times as much 
light. It may be noticed that we have not reduced 
fourteen hundred or sixty-five to their twenty-fifth part, 
as might appear to be the proper course on account of 
the diminution of the sun's light in this degree at 
Jupiter's distance. The reason will be found in what was 
stated in the last paper ' respecting the brightness of 
Jupiter. He is almost three times as bright as a body 
equally large, and placed where he is, but having a 
surface of no greater reflective power than the moon's. 

This leads us to the consideration that possibly a 
portion of the light of Jupiter may be inherent — in other 
words, that he may be glowing with the intensity of his 
own heat. Certainly the excess of his light is not suffi- 
cient to prove this, for as a matter of fact he only gives 
out as much light as he would reflect if his whole surface 
were covered with such clouds as ours. 1 Still, as his light 
is seen in the telescope to be not uniformly white, but 
to owe its whiteness as a whole to a mixture of many 
distinct colours, while some of his belts present an actual 

1 Everyone who has seen the moon by day, when there are small 
summer clouds in the sky under full illumination, must have noticed how 
much inferior the moon's brightness is to that of such clouds. 
5 



92 The Expanse of Heaven. 

red colour, as though there were red-hot matter glowing 
underneath his vaporous envelope, the idea is strongly sug- 
gested that he may glow with some small degree of inherent 
light, and may be capable of supplying a considerable 
quantity of heat to the orbs which circle around him. 

This is not so fanciful as perhaps many readers may at 
first suppose. If we imagine Jupiter to give out as much 
heat as though he were a globe as hot as iron when it is 
beginning to show red with increase of heat, he must 
warm at least his nearer satellites in an efficient manner. 
The quantity of heat he would supply to his nearest 
satellite would be that which a circular sheet of iron, one 
foot in diameter, and maintained at a dull red heat, 
would give out to objects two yards from it. This would 
be by no means a contemptible addition to the supply 
derived directly from the sun. And it is to be remem- 
bered that this heat and any accompanying light would 
be given out not only, like the reflected sunlight, when 
Jupiter is full, but whenever he is above the horizon. 
Thus may it be said of these moons, that 

By tincture or reflection they augment 
Their small peculiar, though for human sight 
Too far remote. 

Apart, however, from such considerations as these, it 
will be manifest that whatever differences may be pre 
sented in the moons of Jupiter as compared with our 
earth, the only known abode of life, are differences of 



Jtipiters Family of Moons. 93 

degree only and not of kind. They are not by any means 
of such a nature as to preclude the conception that life 
exists on these worlds. 

If this be indeed the case, how wonderful must be the 
scene presented to the inhabitants of these moons by the 
great planet round which they circle ! He must, in fact, 
replace with them the great object of our own wondering 
contemplation, the sun. For to them the sun is a minute 
body, showing a disc scarcely equal to one twenty-fifth of 
the sun's disc as we see him; but the glorious disc of 
Jupiter, varying at the several moons from an area 1,600 
times as great as their sun, to an area 35,000 times his, 
and marked by the wonderfully beautiful colours of which 
our telescopes afford a faint idea, must be an amazing 
object of contemplation. The changes also which take 
place in his aspect as he turns round on his axis, and also 
as real changes take place in his cloud envelope, must 
be singularly impressive and suggestive. We may well 
believe that if there are reasoning creatures on the worlds 
which circle around Jupiter, they have as good reason as 
we ourselves to say, < The heavens declare the glory of 
God, the firmament showeth His handiwork.' 



94 The Expanse of Heaven. 



THE RING-GIRDLED PLANET. 

I haye often thought that among the most instructive of 
those lessons which the celestial orbs teach us is the 
avoidance of rash judgments as to the ways and works of 
the Creator. We are so often mistaken when we judge 
by appearances. Some star or planet appears to our 
judgment inferior to the rest, either in size or brightness, 
or beauty of colour, and we should be apt to judge that it 
was among the least important of God's works ; and lo, 
when we see it rightly, it is a miracle of beauty and 
symmetry, marvellous in its dimensions and in the com- 
plexity of its structure, and manifestly a scene where 
forces the most stupendous are daily and hourly in action. 
Certainly there is no known orb which presents so 
strikingly the contrast I have referred to as the planet 
Saturn. To the naked eye this body is a dull-looking 
star, far inferior to Jupiter and Venus in apparent size — 
nay, even surpassed in lustre by Mars and Mercury, the 
least of the primary planets. Slowly he drags his course 
onward from station to station, his slow advance alternat- 
ing with yet slower retrogression. He was chosen by the 
alchemists as the representative of the heavy and lustre- 



The Ring-Girdled Planet. 95 

less metal lead, deleterious in its influence on the body, 
and of little intrinsic value. The astrologers selected 
him as the planet working the most mischievous effects 
on the fortunes of the human race. He was held to be 
not only a mean but an evil planet, aptly named after the 
old time-god, whose cruelty was matched by his dullness 
and stupidity. 

How different is all this to the reality ! We turn on 
Saturn a powerful telescope on some calm clear night, 
when the air is well suited for observation, and we see 
the most beautiful picture conceivable — a glorious orb, 
the surface resplendent with the most beautiful colours, 
blue at the poles, yellow elsewhere, crossed by a creamy 
white central belt, and flecked with spots which under 
favourable circumstances show brown, and purple, and 
ruddy tints. The most wonderful part of the picture, 
however, is the amazing ring-system, not a mere ring as 
it is so often shown, but a complex system of rings, each 
curiously variegated in colour, while the innermost (richly 
purple under favourable observing conditions) is unique 
among celestial objects in being transparent, so that the 
orb of the planet can be seen through this ? crape veil 
ring,' as astronomers have called it. 

The return of Saturn to our midnight skies presents a 
favourable opportunity for an enquiry into what has been 
learned respecting this beautiful planet, the most com- 
plex in construction of all the members of the solar 
system, inferior only to Jupiter in dimensions and mass, 



g6 The Expanse of Heaven. 

while surpassing even that prince of planets in the extent 
and importance of the scheme over which it bears sway. 
I shall proceed in this enquiry on the plan which I have 
heretofore adopted in these pages — not restricting my 
remarks to the mere physical wonders of the object dealt 
with, but endeavouring to present my subject in such a 
way as to indicate something of the purposes which Saturn 
may be supposed to fulfil in the scheme of creation. I 
shall be unable indeed to proceed so far in this direction 
as I should wish, or as some readers may expect. For 
indeed I hold that many writers who, with an excellent 
purpose in view, have attempted to show forth the 
Creator's praise by indicating the plans He had in view 
when this or that arrangement in the universe was de- 
signed, have erred, mistaking their conviction that ' God 
worketh all things according to law,' for the power of 
ascertaining what that law may be. Yet it seems a useful 
and judicious exercise of the reason to endeavour to 
ascertain, where possible, the special purpose which 
various created things subserve in the economy of the 
universe. 

Let us first picture to ourselves the wonderful dimen- 
sions of the ringed planet. He has a somewhat flattened 
globe, whose mean diameter is about 9 times that of 
the earth, so that his surface exceeds hers about 81 
times, while his volume exceeds hers more than 700 
times. But his mass does not exceed the earth's mass to 
so enormous a degree. For, regarding him as a whole, 



The Ring-Girdled Planet. 97 

his mean density is less than that of any known planet, 
being less than a seventh of the earth's, so that he exceeds 
her in mass only about 90 times instead of 700 times. 
But even this is still a very great disproportion ; and, in 
fact, if all the planets except Jupiter were formed into a 
single mass, this mass would be little more than a third 
of Saturn's. 

The globe of Saturn seems to be enwrapped within 
a dense cloud-laden atmosphere, resembling in many re- 
spects that which surrounds the planet Jupiter. In fact, 
for anything which is certainly known, Saturn may have 
no solid globe at all ; for nothing fixed has ever been recog- 
nised in Saturn. We see an orb so enwrapped in cloud 
that all we can perceive, even when the outermost cloud 
layers pass away from any part of the disc, is an inner 
cloud envelope, which, for anything we know to the con- 
trary, may not be the innermost. Indeed, one is per- 
plexed, in enquiring into Saturn's deep and apparently 
dense atmosphere, by the difficulty of understanding how 
that atmosphere can possibly endure the enormous attrac- 
tion to which we know it to be subjected. There is the 
attracting mass oi Saturn drawing that atmosphere always 
down towards the planet's surface (if it has a surface) 
with such force that if much deeper than ours the atmo- 
sphere would actually be compressed into the liquid or solid 
form. 

But there is another singular circumstance closely 
related to the one just mentioned. We might expect 



98 The Expanse of Heaven. 

that the enormous globe of Saturn, containing ninety 
times as much matter as the earth, would be greatly 
compressed by the attraction of its own parts on each 
other. For when we say that his mass exceeds the 
earth's ninety-fold, we in fact imply that his attractive 
energy, his might as a ruler of matter, exceeds the earth's 
in that degree. And what draws the earth's globe to- 
gether, and compresses its inner parts to their present 
degree of density, is the attractive energy of its mass ; 
so that we might expect the inner parts of Saturn to be 
compressed in proportion to his much greater mass, and 
his density consequently much greater. But, as I have 
said, his density is less than a seventh of the earth's. 

How is it, then, that on the one hand Saturn's atmo- 
sphere is so deep and yet so mobile as we perceive it to be, 
while his mean density is less than that of water ? This 
is a question of great importance in connection with the 
question of Saturn's habitability. For when all the cir- 
cumstances are carefully considered, no way of removing 
the difficulty is recognised, except the supposition that 
the density of Saturn remains small and his atmosphere 
remains mobile by reason of an intense heat pervading 
the whole of Saturn's mass. We know of no power except 
heat which could prevent the enormous mass of Saturn 
from producing the effects due to its gravitating energy. 
We see in the sun's globe an illustration of the power 
which heat possesses in this respect. The sun's mass 
exceeds the earth's not ninety times, but three hundred 



The Ring- Girdled Planet. 99 

and fifteen thousand times, and yet his mean density is 
less than one-fourth of hers. But his fiery heat enables 
us to understand this circumstance. It vaporises the 
materials which we regard as the most stable, and expands 
the vapours thus produced. It swells the whole bulk of 
the sun, reducing his mean density not only below the 
density due. to his enormous mass, but even below that 
due to a mass such as our earth's. 

Saturn, however, does not, like the sun, show manifest 
signs of being pervaded by an intense heat. He does not 
glow with inherent light ; and if he emits (as the supposi- 
tion we are dealing with requires) an intense heat, the 
distance at which we are placed from him prevents us 
from becoming sensible of the fact. It is clear, of course, 
that he is not nearly so hot as the sun ; and obviously we 
should not expect this, since his mass is but the 3,500th 
part of the sun's, while his density is more than half as 
great as the sun's. It would suffice to account for Saturn's 
actual density, if he is so hot only that although his real 
globe is glowing with the intensity of his heat, his atmo- 
sphere is non-luminous and loaded, moreover, with opaque 
clouds thrown up from the heated mass within. In this 
case he would appear much brighter than he would if his 
visible surface were like our white sandstone, for the 
clouds in his atmosphere would reflect much more light 
than any kind of earth known to us, shining, in fact, with 
a whiteness nearly equal to that of driven snow. And 
probably a certain quantity of the light from his glowing 



ioo The Expanse of Heaven. 

interior would pass to us between the clouds of his deep 
atmosphere. 

This corresponds closely with the facts observed in the 
ease of Saturn as of his brother giant Jupiter. Both 
these planets shine much more brightly than they would 
do if their surfaces consisted of any known kind of earth. 
This has not only been shown by careful measurement of 
the light received from these planets, but by yet more 
satisfactory evidence obtained by photographing them. 
Lying so much farther from the sun than our moon does, 
much less light falls upon each square mile of their surface, 
and if they were opaque, and of the same reflective power 
as the moon, Jupiter would require about twenty-five 
times the period which is required to photograph the full 
moon, and Saturn about ninety times. But Dr. De La Hue, 
the eminent English photographer, finds that the 
photographic power of the moon exceeds Jupiter's only 
about as 3 to 2, and exceeds Saturn's only as about 15 to 
1. This, indeed, would imply that a considerable part of 
each planet's light is inherent, a result which agrees with 
the estimates of their brightness obtained by Professor 
Bond of America. But we may be content to accept the 
lower estimate of Zollner, the German astronomer, who 
found that Jupiter shines as if he were a globe of white 
cloud, and Saturn as though nearly of the same reflective 
capacity. This is sufficient to show that these two planets 
are quite unlike the earth. Combining with the reasoning 
based on Saturn's low mean density, the cloud-encompassed 



The Ring- Girdled Planet. i o i 

condition of his atmosphere, and his relative bright) 
suggestive of some degree of inherent luminosity, we seem 

tified in arriving at the conclusion that, like Jupiter 
Prince of Planets, Ring-girdled Saturn is not a fit 
abode for living creatures. 

But if, in Jupiter's case, we could torn from the 
primary planet to a scheme of dependent orbs, and regard 
these as the habitable worlds and their primary a 
subsidiary sun, much more is this the case with Saturn. 
For, in truth, the scheme over which Saturn be 
a miniature, and no contemptible miniature, of the solar 
If. Within an extreme span of upwards of 
four millions of miles (two millions on either side of 
Saturn's globe) there circle eight worlds, the least of 
which is probably at least a thousand miles in diameter, 
while the largest, appropriately called Titan, is certainly 
larger than Mercury, and probably as large as Mars. 
Then within the path of the innermost of these bodies — 
these moons, as astronomers term them — there is the 
wonderful ring-system of Saturn. The span of this system 
of rings amounts to about 176,000 miles — that is, its 
outermost edge lies about 88,000 miles (more than eleven 
times the earth's diameter; from Saturn's centre. The com- 
plete system has a breadth of about 37,600 miles; but the 
innermost part, to a breadth of nearly 9,000 miles, is dark. 
Through this dark ring, where it crosses the planet, the 
outline of Saturn's disc can be clearly perceived. In fact, 
this wonderful dark ring is transparent. The bright pi 



i o 2 The Expanse of Heaven. 

of the system form two rings, separated from each other 
by a dark, but not perfectly black, circular division, about 
1,700 miles broad; but it is supposed that each of these 
two ring's is subdivided into a great number of rings, and 
a circular mark, as though the outermost were divided 
into two connective rings of nearly equal width, has been 
seen by several observers. 

Such is the wonderful system over which Saturn bears 
sway, his mighty mass guiding his eight satellites on 
their paths around him precisely as the sun's mass guides 
his eight planet-dependants on their course. It has been 
shown, too, that the ring-system consists of multitudes of 
small satellites, guided also by the attraction of Saturn, 
even as the thousands of bodies in the ring of asteroids 
are guided by the attraction of the sun. 

It seems to me that, apart from the reasoning already 
adduced, we have to choose between two views of the 
Saturnian system. Either the scheme of satellites and 
the system of rings are intended to subserve some useful 
purpose with respect to Saturn, or Saturn subserves some 
useful purpose with respect to these systems. Now, the 
satellites can supply very little light to Saturn. All 
together (if they could be all full together) they would 
supply but a sixteenth part of the light which we receive 
from our moon when she is full. How so insignificant a 
supply of reflected light can make up to Saturnians for 
the fact that the direct supply of solar heat is but one- 
ninetieth of that which we receive, I leave the believers in 



The Ring- Girdled Planet. 103 

Saturn's habitability to explain. But the ring-system, 
which also has been spoken of as supplementing the 
deficiency of solar light, does just the reverse. It deprives 
the Saturnians for long periods together, in some regions 
for several successive years, of the light they would other- 
wise receive. And this it does in the winter of those 
places. At this time, also, it reflects no light to them 
during the night. In summer the rings do not cut off 
any of the sun's light, and they shine at night with a 
considerable degree of brightness, marred only by the cir- 
cumstance that at midnight the great shadow of the planet 
falls on nearly the whole of the visible part of the ring. 
But no supply of reflected light during the summer nights 
can compensate for the deprivation of the whole of the sun's 
direct light in winter for several of our years together. 

We seem compelled, then, to adopt the view that 
Saturn subserves useful purposes to the worlds which 
circle round him. To these he certainly supplies much 
reflected light, and possibly a considerable proportion of 
inherent light. He probably warms them in a much 
greater degree. And it seems no unworthy thought 
respecting him that even as he sways them by his 
attractive energy, so he nourishes them as a subordinate 
sun by the heat with which his great mass is instinct. If 
our sun, so far surpassing all his dependent worlds in 
mass, yet acts as their servant in such respects, we may 
reasonably believe that Saturn and Jupiter act a similar 
part towards the orbs which circle round them. 



104 The Expanse of Heaven. 



NEWTON AND THE LAW OF THE UNIVERSE. 

While the study of astronomy affords many wonderful 
subjects for meditation in the celestial glories which it 
reveals to us, it also gives food for profitable reflection in 
the lessons which it affords us respecting the mental 
powers given to man by his Creator. 

It is, for instance, a strange and suggestive circumstance, 
that man insignificant in his dimensions and in all his 
physical powers, when viewed in comparison even with the 
earth on which he lives, and compelled to remain always 
upon that orb, which is utterly insignificant compared 
with the solar system, should yet dare to raise his thoughts 
beyond the earth and beyond the solar system, to contem- 
plate boldly those amazing depths amidst which the stellar 
glories are strewn. 

That he should undertake to measure the scale on 
which the universe is built, to rate the stars as with 
swift yet stately motion they career through space, to test 
and analyse their very substance, to form a judgment as 
to processes taking place upon and around them, though 
not one star in all the heavens can be magnified into more 
than the merest point — all this affords noble conceptions 
of the qualities which the Almighty has implanted in the 



Newton and tlie Law of the Universe. 105 

soul of man. Nor can I express assent here with the con- 
ceptions of Milton (otherwise so nobly free in his ideas of 
the duties of men), where he describes Raphael as dis- 
suading Adam from enquiry into the profounder problems 
of nature, when our first parent, by his countenance, 

seemed 

Ent'ring on studious thoughts abstruse . . . 

6 This to attain,' says Eaphael, 

' Imports not, if thou reckon right : the rest 
From man or angel the Great Architect 
Did wisely to conceal, and not divulge 
His secrets to be scanned by them who ought 
Eather admire ; or, if they list to try 
Conjecture, he his fabric of the Heavens 
Hath left to their disputes, perhaps to move 
His laughter at their quaint opinions wide 
Hereafter ; when they come to model Heaven 
And calculate the stars . . . 
Solicit not thy thoughts with matters hid ; 
Leave them to God above ; him serve, and fear ! 
Of other creatures, as him pleases best, 
"Wherever placed, let him dispose ; joy thou 
In what he gives to thee, this Paradise 
And thy fair Eve. Heaven is for thee too high 
To know what passes there. Be lowly wise ; 
Think only what concerns thee, and thy being ; 
Dream not of other worlds, what creatures there 
Live, in what state, condition, or degree, 
Contented that thus far hath been revealed 
Not of Earth only, but of highest Heaven/ 

Far nobler, as it seems to me, is the thought of our Poet- 
laureate : — 

Let knowledge grow from more to more, 

But more of rev'rence in us dwell, 

That mind and soul according well 
May make one music as before, 



106 . The Expanse of Heaven. 

But vaster. We are fools and slight, 

We mock Thee when we do not fear. 

Ah, teach Thy foolish ones to bear, 
Teach Thy vain worlds to bear Thy light. 

Certainly man ' then seems likest God ' when he exercises 
the noblest of the powers which God has given him. Grod 
sees ; and, in his infinitely feebler way, man sees : but we 
express the attributes of the Almighty more fully when 
we say Grod sees and knows, that is, God sees and under- 
stands ; and, in like manner, we indicate a nobler quality 
in man — a more distinguishing attribute — when we note 
his power of understanding what he sees. 

Slowly, it is true, does the power of the mind give to 
man the mastery over the more hidden ways of nature. 
One after another tries and fails, though gradually accu- 
mulating the knowledge by which, in the end, the secret 
will be learned. At length the master-mind arrives which 
is to utilise the garnered knowledge of ages. On a sudden 
the scattered portions of the chain of evidence are linked 
together, and the chain is complete. A great work has 
then been achieved — a work which the Almighty had as 
fully intended that the human race should accomplish 
as any of those material successes by which men have 
obtained mastery over nature and the forces of nature. I 
would not join with those who have spoken of the scien- 
tific apotheosis of man. Indeed, I conceive that science 
teaches no lesson more plainly than the feebleness of man, 
and the narrow range of the mental powers of individual 



Newton and the Law of the Universe. 107 

men — even the most eminent in science. But the scien- 
tific successes of mankind stand far higher than any others 
which they achieve, except those only in which they 
master themselves. We may not be satisfied in studying 
nature until we have passed ' from nature up to nature's 
God ; ' but scientific research is a good guide, if rightly 
followed, for a great part of the journey. 

Few instances afford a more remarkable illustration of 
the true nature of scientific research in this respect — not 
merely in the wonders which it reveals, but in its own 
wonderful nature — than the enquiry by which the great 
Sir Isaac Newton was led to the discovery of the law of 
gravitation. 

For many long years astronomers had been engaged by 
observation, calculations, and reasoning based on these pro- 
cesses, in the endeavour to ascertain the laws according to 
which the planets move. After a long struggle to retain 
the earth in her apparent position as the chief body and 
true centre of the universe, they had been led by the 
masterly investigations of Copernicus to the theory that 
the sun is the ruling orb of the solar system. Then the 
ingenuity of Kepler, following on the laborious and skilful 
observations of Tycho Brahe, had revealed certain laws of 
planetary motion. It was shown by him that the planets 
revolve in ellipses (very nearly circular) around the sun, 
placed, not in the centre, but at one of the points called the 
foci of the ellipse. He had ascertained also that each 
planet, in travelling around this common focus, so moves 



108 The Expanse of Heaven. 

that if a long elastic cord were supposed to connect this 
planet with the sun, this cord would sweep over equal 
surfaces in equal times ; a singular discovery reflecting 
great credit on Kepler's ingenuity and patience, since it is 
not such a law as would occur until after many others had 
been tried and rejected ; and there was no reason known 
to Kepler why so peculiar a law should be followed. In 
fact, we know that he was engaged no less than nineteen 
years in testing various laws before he succeeded in dis- 
covering the true one. Then a third law, the most re- 
markable of all, was discovered by Kepler. 

The other two laws related to each planet severally. 
But now he discovered a law connecting the various planets 
together, a law exceedingly simple, though like many 
other simple matters it can be made to sound exceedingly 
recondite by the use of a few long words. I dare say many 
among my readers would start away in disgust from this 
essay, if I assured them solely that the planets so move 
that their periods are in the sesquiplicate ratio of their 
mean distances. But the third law of Kepler may be 
more pleasantly indicated. It is this : — If we take the 
number <j£ days in which a planet revolves round the sun, 
and multiply that number into itself once, and if we then 
take the number expressing the distance of the planet from 
the sun in miles, and multiply that number into itself 
twice over, we shall find that the two numbers we 
thus obtain bear always a constant proportion to each 
other. There is no difficulty in verifying the law as thus 



Newton and the Law of the Universe. 109 

stated ; but the process is long, so I will give the law in 
another form much more readily verified. Take the year 
for the unit of time, this being the earth's period of revo- 
lution, so that in fact we call the earth's period 1. Call 
her distance from the sun 1 also. Then the following 
simple law holds : any planet's period multiplied twice 
by itself is represented by the same number as the same 
planet's distance multiplied once by itself. Thus a table 
of the planets' elements gives us for Jupiter's period nearly 
11*9 years, and for his distance 5*2 times the earth's. 
Now, if we multiply 11*9 by itself once, we get the 
number 141*61 ; and if we multiply 5*2 by itself, we get 
27*04, which multiplied again by 5*2, gives 140*608. 
This number we see is very nearly equal to the other ; and 
it would have been exactly equal, if we had taken the 
exact number : for Jupiter's orbit is rather less than 11*9 
years, and his distance rather more than 5*2 times 
the earth's. The same would be observed if we tried any 
other planet. Here, then, was a law by which in some 
mysterious way the planets seemed to be associated 
together, moving with a harmony corresponding in some 
sort to that which the Pythagoreans of old had be- 
lieved in. 

It was thus that Kepler viewed this last discovery of 
his. His fervent disposition was roused to earnest enthu- 
siasm when he had found this law of harmony in the 
universe. He felt instinctively that he was approaching a 
yet grander discovery, or that at least he had shown the path 



no The Expanse of Heaven. 

by which a greater truth was to be reached, and the law 
of the universe recognised. He might have spoken of 
himself, had he known what was to come, as the Moses of 
the astronomy of the future, who saw the promised land 
afar off, but entered not therein. But he chose rather to 
use the words of the ancient mystics : ' I will rejoice ! ? he 
exclaimed ; ' I will triumph in my sacred fury ; for I have 
found the golden vases of the Egyptians ! ' l 

But it was not till Newton came that the true meaning 
of these laws was ascertained, and very wonderful is the 
history of the process by which he solved the noble 
problem which Nature had presented to mankind for in- 
vestigation. Everyone has heard the story of the apple, 
whose fall is said to have suggested to Newton the 
great discovery for which his name will be deservedly 
celebrated for all time. The story may be true in a sense, 
though not in the sense usually given to it. Newton 
certainly did not ask why the apple fell, since it was well 
understood in his day, and had been known for many cen- 
turies, that bodies fall to the earth by virtue of her attrac- 
tive influence. But it is quite possible that Newton, who 
had long been engaged in profound meditation on the 
laws of planetary motion, should have suddenly seen 
revealed to him the possibility that a far wider law of 
attraction exists. His mind was full of the thoughts sug- 

1 Kef erring to the belief of the Pythagoreans that certain sacred 
secrets were preserved in golden vases shown to Pythagoras by Egyptian 
priests. 



Newton and the Law of the Universe. 1 1 1 

gested by the mysterious energies which appear to sway 
the motions of the planets ; and here, suddenly, his 
attention was called to the mysterious energy by which 
the earth draws bodies to her surface. "What if one and 
the same form of force is exerted in all such cases ? What 
if the sun draws the planets towards him, as the earth 
draws unsupported bodies towards her ? What if the 
law exemplified in the fall of the apple is a universal law, 
indicating a property of matter itself, not limited to this 
or that kind of matter, but common to all matter and 
exerted on all matter, operating as certainly on every 
particle of the thin air we breathe as on the heaviest 
metals ? 

Newton at once saw that it was to the moon we should 
look for an answer to these questions. And, by the way, 
I might add to the advantages we derive from having a 
moon the fact that but for her we should assuredly not be 
now acquainted with the law of the universe. The moon 
supplied Newton with an intermediate stepping-stone 
enabling him to pass over the wide gap separating terres- 
trial gravity from the sun's action as ruler of the planetary 
system. The earth has an orb circling round her as the 
planets of the sun ; l and the orb thus obeying her attrac- 

1 This is not inconsistent with what I formerly said as to the moon 
circling in reality around the sun. The fact is, that if we consider the 
moon's motion solely with reference to the earth, taking no account of their 
common motion around the sun, then the moon may be regarded as circling 
round the earth. It is only as viewed from some standpoint far away from 
the solar system that the moon must be regarded as an orb circling round 
the sun. Both views are just. 



ii2 The Expanse of Heaven. 

tion was shown by Newton to be subject to a degree of 
force corresponding precisely to the force which the earth 
exerts on bodies which fall to her surface, on the supposi- 
tion that the force diminishes with distance from the 
earth's centre, according to a certain easily explained law. 
At twice the distance the law is reduced to one-fourth, at 
thrice the distance to one-ninth part, and so on. Now, 
the importance of this fact resides in the circumstance 
that, granting this to be the law of diminution in the 
sun's attracting force also, then — all Kepler's laws are 
explained. The planets ought to travel in paths such as 
they actually follow ; they ought to move at rates varying 
as their rates of motion actually vary ; and, lastly, the 
third law, which Kepler called the harmony of the system, 
is, like the others, a necessary consequence of the law 
according to which the solar action diminishes with 
distance. 

Only one kind of evidence was required to make the 
demonstration of the law complete. The general motions 
of the moon, the planets, and the planets' families had 
been fully accounted for. But if the law of gravitation is 
true, then these different bodies must disturb each other. 
The planet Jupiter must disturb our earth, for example, 
as she circuits round the sun, and must disturb the moon 
as she circuits round the earth. Of all such instances of 
disturbance the most marked and the one we could 
recognise best should be the disturbance of the moon by 
the sun. Instead of following the course round the earth 



Newton and the Law of the Universe. 1 1 



o 



which she would have if the earth were the sole centre of 
her motion, the moon would be now swayed on one side 
and now on another side of her course, now hastened and 
now checked, by the sun's disturbing influence. 

It was in dealing with these disturbances that Newton 
showed with what wonderful mental powers he had been 
endowed. He tracked the moon through all her move- 
ments, and measured the sun's action on her in all 
positions; he showed where she-would be hastened, where 
retarded, where drawn away from the earth, where drawn 
closer, where her path would be more tilted, where less, 
where its eccentricity would be increased, where di- 
minished. All the peculiarities of motion thus calculated 
from the law of gravitation were found to accord in the 
most convincing manner with those peculiarities actually 
observed in the moon's motions which had long perplexed 
astronomers. The demonstration of the law of gravitation 
was so complete, as it thus first came from Newton's 
hands, that within a very short time men of science were 
thoroughly convinced, and the law of gravitation has not 
been seriously questioned from that day to this. 

Such is a brief history of the greatest scientific dis- 
covery ever made by man — the recognition, in fact, of the 
law of the universe — a law affecting every particle of 
matter, operating at all distances, ruling the tiniest sand- 
grains, and swaying the mightiest orbs — the. universal law 
of gravitation. 



1 14 The Expanse of Heaven. 



TEE DISCOVERY OF TWO GIANT PLANETS. 

The history of astronomy presents two remarkable instances 
of the discovery of planets. In the present day the dis- 
covery of objects which by courtesy are called planets is 
not an uncommon event. Not a year passes without the 
recognition of two or three and sometimes ten or twelve of 
those bodies termed asteroids, which travel between the 
orbits of Mars and Jupiter. These bodies, so far as their 
motions are concerned, resemble the planets. But they 
are very minute compared with even the smallest of that 
family of minor planets to which our earth belongs. Our 
moon and the satellites or secondary planets which attend 
on Jupiter, Saturn, and Uranus are gigantic bodies com- 
pared with the largest of the asteroids, or, as they are 
sometimes called, the planetoids. And then the zone of 
asteroids is so crowded that no very great interest or im- 
portance can be attached to the detection of new members 
of this family. Already their number is approaching the 
middle of the second hundred, and ' the cry is " Still they 
come." ' 

Luther, the German astronomer, has discovered 
nineteen, and until lately stood easily first among asteroid- 
hunters ; but Peters, of America, has been gaining steadily 



The Discovery of Two Giant Planets.. 1 1 5 

during the last two or three years, and a few weeks ago 
discovered his nineteenth astejoid, so that now Luther and 
Peters are level. Several other astronomers have dis- 
covered more than a dozen of these bodies ; and our own 
countryman Mr. Hind, notwithstanding numerous other 
astronomical engagements occupying the greater part of 
his time, has discovered ten asteroids. It will be under- 
stood, then, that when a new asteroid is detected, astro- 
nomers hear of the discovery with equanimity. 

The two instances with which I propose now to deal 
are of another kind, however, and each in its special way 
attracted deservedly a great amount of attention, while 
one of them has been characterised by Sir John Herschel 
as the greatest discovery since Newton's day. I refer to 
the detection of the two giant planets Uranus and Neptune, 
one discovered accidentally, the other by a process of 
reasoning so profound and difficult that few can even 
understand its force. 

Although Uranus was discovered by accident, it will 
not be thought that on that account small credit should 
be given to Sir W. Herschel, the astronomer to whose 
redoubtable telescope this planet fell as a spoil. The 
accident was one which could not have happened but to an 
enthusiast in astronomical researches. He had penetrated 
into the star depths again and again with telescopes of his 
own construction, engaged in the attempt to solve problems 
of the utmost difficulty, when one night this new orb 
swept into his ken. 



1 1 6 The Expanse of Heaven. 

Even then lie must have failed to know it for what it 
was, or rather he would have mistaken it for what it was 
not — a fixed star — but for the £reat power of the instru- 
ment he was employing ; for so far off is Uranus, that not- 
withstanding its dimensions, which are so great that 
seventy-four such globes as our earth could be formed 
from it, 1 it appears in ordinary telescopes without any 
well-defined disc. Herschel himself could only see that 
the new orb differed somewhat in appearance from a fixed 
star, until, applying higher powers, he recognised the fact 
that he had discovered either a comet or a planet. Then 
he watched for the signs of motion which every comet or 
planet exhibits. He found in a short time that the 
stranger was in motion, and thus £ll doubt was dispelled 
so far as the question whether it was a star or not was 
concerned. 

I do not describe the process of observation by which 
the true nature of Uranus was discovered, the planet's 
orbit determined, the size and mass of the stranger esti- 
mated, 2 and eventually a family of satellites found to be 
travelling around it. My present purpose is to consider 
only the discovery of this planet and its fellow giant 
Neptune. But one singular feature in the history of sub- 



1 This remark refers to the volume of the planet ; in mass it only ex- 
ceeds the earth 12 J times. 

2 A full account of these circumstances, and of recent discoveries 
respecting Uranus, will be found in an essay called 'News from Her- 
schel's Planets,' in the second series of my * Light Science for Leisure 
Hours/ 



The Discovery of Two Giant Planets. 117 

sequent research must be mentioned, not only as bearing 
on the subject of the discovery of Uranus, but because it 
is also connected with the discovery of Neptune, as will 
presently appear. 

So soon as astronomers had recognised the nature of 
the path of Uranus, so as to be able to predict the motions 
of the planet, they could also trace back its course, so as 
to find where it had been at any given time before its 
discovery. Now, when this had been done, it was found 
that Uranus had in reality been often observed before — no 
less than nineteen times in fact. 

It had been observed by the eminent astronomers 
Flamsteed, Bradley, Mayer, and Lemonnier. Flamsteed 
had seen it five times, each time recording its place as 
that of a star of the fifth magnitude. But Lemonnier had 
actually seen the planet no less than twelve times. Un- 
fortunately, Lemonnier was not an orderly man; 'his 
astronomical papers,' says one who has recently written on 
the subject, 6 are said to have been a very picture of chaos;' 
and M. Bouvard narrates that he had < seen one of Lemon- 
nier's observations of this very star written on a paper 
bag which had contained hair powder.' So narrowly had 
the planet escaped recognition until its discovery should 
come to reward the most laborious of all astronomers — the 
great Sir W. Herschel. 

Time passed on, and the slow-moving Uranus began 
to be regarded as a regular member of that family of 
bodies which astronomers watch over with special care. 



1 1 8 The Expanse of Heaven. 

The motions of the planet were carefully calculated and 
as carefully watched; the elements of the planet were 
assigned; and all seemed settled as respected its position 
in the planetary scheme. So complete was the mastery 
which astronomers had gained, since the discoveiy of the 
law of gravitation, over the movements of the planets, 
that long before Uranus had completed the circuit of its 
orbit, all the characteristic features of that orbit, as its 
inclination, eccentricity, and the period (eighty-four years) 
in which Uranus traverses it, had been satisfactorily de- 
termined. 

This was a great triumph for the theory of gravitation ; 
but a far greater triumph was at hand. 

It was found that Uranus did not strictly follow the 
path assigned to it. Not only as time progressed was the 
discrepancy more clearly recognised, but it was found 
absolutely impossible to reconcile the observations made 
by Flamsteed and Bradley, before the discovery of Uranus, 
with the elements which nevertheless astronomers felt 
they could confidently assign to the planet. The disturb- 
ing influence of Jupiter and Saturn, the only planets 
which could affect Uranus appreciably, had of course been 
duly taken into account ; and the masses of these planets 
had been far too satisfactorily ascertained to leave any 
doubt as to the effects which they could severally produce 
on Uranus. Yet the planet's motions still differed from 
those which theory assigned. 

The idea was quickly broached that there must be an 



The Discovery of Two Giant Planets. 119 

orb travelling outside Uranus, and disturbing the planet 
by its attractions. Bouvard was the first, I believe, to 
suggest this natural explanation, which astronomers 
readily accepted as sufficient. The idea was certainly 
strange, and startling because of its novelty. Here was 
a planet which has been known only for half a century, 
and because it was now a little on one side and now a little 
on the other side of its estimated position, astronomers in- 
ferred that another planet as yet unseen was disturbing 
their new friend. 

But was it impossible to discover the unseen planet by 
carefully taking into account all the discrepancies in the 
movements of Uranus ? Probably the daring nature of 
this conception can only be appreciated by mathematicians, 
who know the enormous difficulty and complexity of the 
problem involved. To others it might seem, perhaps, that 
the displacement of Uranus would point directly enough 
to the place of the disturbing planet, just as, let us say, 
the strain on the angler's line would indicate very clearly 
the place of the unseen fish which produced that strain. 
But in reality this is a very incorrect way of viewing the 
matter. 

It is one of the most difficult problems that can be 
imagined to determine the motions of a planet when all 
the circumstances which can affect that motion are known. 
For instance, long after the theory of gravitation had been 
established, the most skilful mathematicians failed one 
after another in explaining a certain marked peculiarity in 



1 20 The Expanse of Heaven. 

the movements of Jupiter and Saturn, although in reality, 
as Laplace afterwards proved, that peculiarity was a neces- 
sary consequence of relations already known to exist between 
those two planets. Now, only conceive how enormously 
difficult the converse problem must be when the direct 
problem is so difficult. If when we take two known 
planets of given mass, distance, and so on, we find it ex- 
tremely difficult to determine in what way each planet will 
affect the other, how exceedingly difficult — might we not 
even imagine, how utterly impossible — it must be to infer 
from the peculiarities of motion of one planet the distance, 
mass, and position of a planet hitherto unknown ! This 
was the problem which lay before astronomers, and all save 
two shrank from the attempt to solve it. Of these two one 
was a young man who was preparing to take his degree at 
Cambridge — John Couch Adams, destined to be soon re- 
garded as the greatest mathematical astronomer England 
has had since Newton's day. The other was the French- 
man Leverrier, Adams's senior in years, possessed of far 
more complete information of the facts of the case, and 
of far more abundant leisure to deal with the problem. 

Yoimg Adams first completed his work. He estimated 
the place of the as yet unseen planet, and announced it 
to the Astronomer Eoyal for England. Challis also, the 
head of the Cambridge observatory, received the news. 
Between these two observatory chiefs it might be thought 
that the new planet, if it lay anywhere near the indicated 
place, would be quickly discovered. But Professor Airy 



The Discovery of Two Giant Planets. 121 

seemed to imagine that a mare's nest had been dis- 
covered. He put some questions intended to be posing, 
which the young Johnian was not eager to answer. 
Challis was more zealous in the cause of science. He 
did all he could be expected to do, especially when we 
remember that he quickly learned that the Astronomer 
Royal had small faith in the superior mathematical power 
of his young contemporary. It may perhaps surprise 
some readers to learn that Challis actually saw the planet. 
He saw it twice, and each time marked its place. The 
planet was in the net. Nothing, it should seem, could 
lose England the credit of the greatest astronomical feat 
since Newton's day. But, to quote an old proverb, the 
cards never forgive. The Astronomer Eoyal had challenged 
ill fortune for England, and ill fortune came. It was in 
September 1845 that Adams had communicated to Challis 
the place of the disturbing planet, and in October that in 
the pleasing confidence of youth he had forwarded the 
information to the Astronomer Royal. 

In June 1846, or fully eight months after Adams's first 
intelligence, Leverrier 4 assigned,' to use Challis's words, 
c very nearly the same longitude for the probable position 
of the planet as Mr. Adams had arrived at.' But even 
then the information Leverrier gave was not so complete 
as that which Adams had given, for Adams stated the form 
and position of the orbit, the mass, and the mean distance 
of the hypothetical planet, whereas Leverrier 'gave no 
results,' says Challis, ' respecting the planet's mass and the 



1 2 2 The Expanse of Heaven. 

form of its orbit.' Shortly after the Astronomer Royal 
began to think that possibly Adams might after all be 
right. But it was now too late. For the Berlin astrono- 
mers, six weeks after Challis had secured two observa- 
tions of the planet, detected it from Leverrier's announced 
place. It is only necessary, to make the story complete, 
to mention that as soon as Challis, Sir John Herschel, 
and others announced what Adams had really effected, 
Arago and other French astronomers abused our great 
young Englishman as an interloper, as though it were 
incredible that the country of Newton should have pro- 
duced the equal of Leverrier. 

I must not dwell further, however, on the circum- 
stances of this discovery, preferring to deal with the 
pleasanter considerations suggested by its nature. It 
seems to me in some respects even more striking than 
Newton's discovery of the law of gravitation. Newton 
explained the laws according to which known objects move ; 
Adams and Leverrier showed where a hitherto unknown 
object would be found when telescopes were turned to 
that part of the heavens. Newton recognised laws 
hitherto unknown. Adams and Leverrier by abstract 
reasoning inferred the existence of a world which men as 
yet had never seen. 

But there is one consideration which is even more 
suggestive. The acutest reasoners among men have been 
able to detect a planet by means of the disturbances pro- 
duced by its attraction acting on the planet which travels 



The Discovery of Two Giant Planets. 123 

nearest to it. But if the mental powers of man were in- 
creased he could analyse disturbances much more minute 
in their effects. We can conceive so great an increase of 
power that, from the motions of one planet only, the 
nature of the whole solar system might be inferred. But 
to the infinite wisdom of the Almighty a power of in- 
ference such as this is as the weakness of the infant's 
mind compared with the powers of a Newton. To Him 
the least grain indicates the whole scheme of the universe, 
its present condition, past history, and future fate. Not 
an atom in the remotest orb can move a hair's breadth 
without producing in every other atom throughout the 
universe an effect — infinitely minute to our perceptions — 
but as manifest to the Almighty as the noon-day sun to 
us. Man reaches the limit of his powers in reasoning 
from one planet to the next ; to the Almighty every atom 
in infinite space is eloquent of the universe itself. 



124 The Expanse of Heaven. 



THE LOST COMET. 

And I looked, and behold, a great cloud came out of the north, and a 
fire enfolding itself, and a brightness was about it, and out of the midst 
thereof as the colour of amber, out of the midst of the fire. — Ezekiel i. 4. 

These words describe, not inaptly, what was seen on the 
evening of November 27, 1872, in Italy and other countries 
where the atmosphere was clear. Here in England there 
was a display of shooting-stars, some forty or fifty thousand 
of these bodies falling between the hours of five and 
eleven. But wonderful as was this display, in Italy a yet 
more unusual spectacle was witnessed, for at the height of 
the display the smaller meteors were so numerous that the 
appearance presented was that of a cloud of light around 
the gemmed feet of Andromeda in the northern skies ; 
6 a great cloud came out of the north, and a fire enfolding 
itself, and a brightness was about it.' Moreover, since the 
larger meteors shine for the most part with a yellowish 
light, it may be said that ' out of the midst of the cloud 
came a brightness as the colour of amber, out of the midst 
of the fire.' 

Soon after it was announced that the meteors forming 
this wonderful display were travelling on the track of a 



The Lost Comet 125 

lost comet, known to astronomers as Biela's. A score of 
years had passed since this famous, though small, comet 
had been seen. In 1866, and again in the autumn of last 
year, astronomers had searched for it with special care, 
because, according to their calculations, it should have 
been favourably placed for observation. But not a trace 
of it had been detected. Then the expectation arose that 
as the earth was to pass, during the last week in Novem- . 
ber, through the track or wake of the comet, a meteoric 
display might be seen, even as had happened year after 
year when on November 13-14, 1866, 1867, 1868, &c, 
the earth passed through the track of Tempel's Comet. 
This anticipation was actually fulfilled, and it was readily 
shown that all the circumstances of the star-shower agreed 
with the theory that the falling stars were travelling in the 
path of the missing comet. 

But a singular event followed. A German astronomer 
conceived the idea that as the comet's meteor-train had 
come as a star-shower ' from out of the north,' the meteors 
might be looked for as a cloud passing away towards the 
south. He telegraphed to an English astronomer occupying 
a station where the southern skies can be observed, and 
urged him to examine the part of the heavens directly 
opposite to the feet of Andromeda, whence the meteor 
shower had seemed to rain upon our northern regions. It 
was done : and lo ! close to the very spot pointed out there 
was. a faint celestial cloud, resembling in all respects a 
small comet. It was watched, and seen to be travelling 



126 The Expanse of Heaven. 

in a course corresponding with that which the lost comet 
would have followed if travelling on that part of its 
path. In fact, the English astronomer announced definitely 
that he had found the comet which had been so long 
missing. 

But it was not so. He had indeed found a nebulous 
cloud of light travelling in the track of the lost comet; 
but when enquiry came to be made by comet-calculating 
astronomers, it was seen that the cloud which had been 
seen in the south was far behind Biela's comet — millions 
of miles, if we count by distance, and nearly a quarter of 
a year, if we count by time, 

Biela's comet is therefore still missing, though it can- 
not be said that we have seen nothing of it. Those meteoric 
visitants had undoubtedly once belonged to it ; that cloud 
of light travelling southwards was unquestionably a portion 
of it, not a fragment recently detached (for such a frag- 
ment would not quickly be left so far behind), but a 
portion, which, many centuries ago, must have formed 
part of the long lost comet. 

But how strange are the thoughts suggested by these 
circumstances ! The history of Biela's comet had long 
been remarkable in cometic annals. In 1832 the comet 
had terrified the nations, because astronomers had 
announced that it would cross the earth's path. 1 In 1846 

1 The account of the terror then excited is very remarkable. The 
anxiety experienced in France led a Parisian Professor to beg the Academy 
of Sciences to refute the assertion that the comet would encounter the earth. 



The Lost Comet 127 

it divided into two separate comets, which travelled side 
by side with a gradually increasing distance between them, 
and with a singular interchange of light, now one onw the 
other being the brighter. In 1852 the comet returned 
yet again to our neighbourhood (the period in which it 
circles around the sun being about six years and eight 
months); and at that time the two companion comets 
could still be discerned, though the distance between 
them had enormously increased. Whether it returned in 
1858-9 is not known, as its arrival on that occasion 
would have carried it to parts of the sky too close to the 
sun for telescopic scrutiny. In 1866, however, it should 
have been seen. Astronomers had become very familiar 
with the calculation of its motions, their predictions 
according better and better at each return with the actual 
motions of the comet ; and the path assigned to it was so 
placed that the comet should have been well seen. But 

' Popular terrors/ he wrote (I quote from Dr. Dick's ' Sidereal Heavens '), 
1 are productive of serious consequences. Several members of the Academy 
may still remember the accidents and disorders which followed a similar 
threat, imprudently communicated to the Academy by M. de Lalande, in 
May 1773. Persons of weak minds died of fright, and women miscarried. 
There were not wanting people who knew too well the art of turning to 
their advantage the alarm inspired by the approaching comet, and places in 
Paradise were sold at a very high rate. The announcement of the comet in 
1832 may produce similar effects, unless the authority of the Academy 
apply a prompt remedy ; and this salutary intervention is at this moment 
implored by many benevolent persons.' Recently an announcement of a 
similar kind, relating to the arrival of a comet on August 12, 1872, 
was received (so far as I have been able to learn) with exemplary 
equanimity. Certainly no ' places in Paradise ' were disposed of on this 



128 The Expanse of Heaven. 

though carefully sought for with large and powerful 
telescopes, it was not then found ; nor again was it seen 
on its return last autumn. 

Let us follow the comet in imagination as it passed 
away from our neighbourhood in the year 1852, and try 
to conceive the dangers and vicissitudes to which it has 
been exposed, and to some one or other of which it may 
perchance have fallen a victim. 

Biela's comet always arrived from out the north, and 
passed away from our neighbourhood southwards. Its 
course did not carry it very much nearer to the sun than 
our earth is ; and, after passing southwards, until it was 
about eighty millions of miles from him, it gradually 
receded again, still passing farther and farther south of 
the general level in which the planets travel. For aught 
that is known, however, it may have been in this part of 
its course that the comet experienced the disturbances 
which so dissipated its substance as to render it undis- 
cernible by terrestrial astronomers. "We have reason to 
believe that meteoric systems are more and more densely 
strewn the nearer the sun is approached, that they cross 
and interlace in wonderfully complex fashion close by 
him ; and it may have been in its passage through such 
labyrinthine meteor-systems that the comet lost its head 
in the most literal sense of the words. Such was the 
opinion of our great astronomer, the younger Herschel, 
who, writing in 1866, when the comet was first missed, 
said, 'Peradventure it has plunged into and got bewildered 



The Lost Comet 1 29 

among the rings of meteorolites.' All that we know of 
the structure of a comet's head teaches us to believe that, 
minute and scattered as are the meteors comprising such 
rings, they are quite sufficiently compact to effect the 
destruction of a comet impinging full upon one of their 
clustering aggregations. 

But let us suppose that the comet escaped this danger 
— and, in any case, we know that what has here been 
spoken of as destruction is not absolute annihilation, but 
only the destruction of the cometic form : it passed on, 
let us imagine, unscathed by the meteors which crowd 
round the sun's neighbourhood, and, gradually increasing 
its distance, it bore away towards those cold regions of 
interplanetary space which lie beyond the orbits of the 
earth and Mars. Obeying the mighty reining power of 
the sun's attraction, the comet travelled on its oval path, 
sweeping far to the south of the orbit of Mars, and pre- 
sently, as its distance still increased, it began to return 
towards the general level in which the planets travel. 
What strange news would that comet have to tell, if it 
could describe all the scenes through which it passed in 
this portion of its path ! 

Meteor-streams unknown to terrestrial astronomers 
travel in countless thousands in those spaces. Isolated 
bodies, like those aerolitic masses which fall from time to 
time upon the earth, are moving hither and thither on 
their paths round the sun. And yet more wonderful must 
be the scene presented by the solar system itself, and the 



1 30 The Expanse of Heaven. 

star depths surrounding it. We are so in the habit of 
regarding the visible half-sphere of the heavens as a star 
canopy, at night, over the seemingly level earth, that it is 
difficult to conceive the complete starlit sphere within 
which each of the members of the sun's family really 
travels. And how wonderful must be the aspect of our 
sun seen from the interplanetary spaces without the inter- 
vention of that atmosphere of ours which veils his glories ! 
The coloured prominences, and the deeply-hued sierra, 
would be clearly visible from such a standpoint, while 
around all would be seen the glorious corona with its com- 
plicated structure branching outwards into space, and, 
perhaps, mingling with the softer lustre of that immense 
disc of scattered matter which astronomers call the 
zodiacal light. 

As our comet travelled towards the level in which the 
planets move, it was exposed to a new form of danger. 
Between the paths of Mars and Jupiter lies the zone of 
small planets. It is probable that there are myriads' of 
these bodies of all orders of magnitude from the largest — 
Vesta, Juno, and the others first discovered — to bodies 
perhaps as minute as the least of the meteors. Astrono- 
mers have already discovered 130 of these small planets, 
and continue yearly to discover more, while it is probable 
that the smaller members of the family will for ever 
remain undetected. Now, these bodies present a form of 
danger to cometic wanderers which the large planets do 
not occasion. They do not travel in the same general 



TJie Lost Comet. 131 

level as the large planets, but at considerable inclinations 
thereto ; and thus they range widely above and below that 
level. The width of the zone is also considerable. In 
fact, the zone does not form a flat ring like the ring of 
Saturn, but a system shaped like an anchor ring. 1 
Through this zone, or at least its outskirts, the path of 
Biela's comet carries it ; and it is not altogether impos- 
sible that it was while passing through this critical part of 
its orbit, that it suffered the injuries which have prevented 
it from returning in recognisable form to the scrutiny of 
our terrestrial astronomers. 

But if it only escaped that danger, it was thence- 
forward safe until it again returned to the earth's path. 
It had to pass, indeed, the orbit of giant Jupiter, who is 
the great disturber of comets, insomuch that a fanciful 
mind might recognise no inapt description of this planet's 
qualities in the title ' cloud-compeller,' given by Homer 
to Zeus, the Jupiter of the Greek mythology. But there 
is no danger to Biela's comet in this part of its career, 
since his course carries him far to the north of Jupiter's 
orbit. Travelling still farther outwards to the point of 
its path farthest from the sun, the comet then returns, 
rounding the zone of small planets at a safe distance, passing 
far north of the course of Mars, and thence, with con- 



1 This is the technical name for such rings. Possibly to most of my 
readers a wedding-ring will seem to present an apter illustration. A wed- 
ding-ring would, in fact, be called by a mathematician an 'anchor-ring;' a 
term not unsuitable, perhaps, in other respects. 



132 The Expanse of Heaven. 

tinually increasing rapidity, descending towards the path 
of the earth as a ' cloud coming out of the north.' 

Since the comet was last seen it has thrice traversed 
the enormous orbit here described, passing from a least 
distance of about eighty millions of miles to its greatest 
distance amounting nearly to six hundred millions of 
miles. Whether it has been destroyed as a comet, or 
whether it has only been so far dissipated as to be invisible 
in our most powerful telescopes, we do not know. But in 
either case it has pursued the same general course, for the 
minutest fragment of its substance would obey as implicitly 
the law of gravity as the once complete comet, or even 
as the staider members of the solar family — the planets. 
Such have been the motions of this singular object, such 
the vicissitudes to which it has been exposed. There is 
much that is mysterious in these events, much that, to our 
feeble conception, appears like a waste of energy. But 
we must remember that though we are ignorant of the 
purposes which the comet has fulfilled in its journeyings, 
and of the effects which have resulted from its dissipation, 
yet all that has happened to it during its career as a 
member of the solar family was designed by Him who 
< foresees the end from the beginning.' ' Great and mar- 
vellous are Thy works, Lord God Almighty I • 



VISITANTS FROM THE STAR DEPTHS. 

There are some astronomical facts which do not seem at 
a first view more surprising than others, but which yet, 
when studied thoughtfully, disclose the most startling 
thoughts for our consideration. Among these I know 
none more remarkable than the fact that certain bodies 
reach our solar system from the stellar depths. The fact 
is easily stated ; and at first we might be disposed to say 
that it is not particularly surprising. If the spaces round 
our solar system are tenanted by stars, why should they 
not be tenanted by comets, or by flights of meteors ? and 
such bodies existing in the star depths, why should they 
not from time to time be drawn from out those depths by 
the sun's attractive energy, or be encountered by the solar 
system as it speeds onwards through space ? 

But so soon as we begin to enquire into this now 
undoubted fact, we find ourselves brought face to face with 
mysteries of the most perplexing nature, and we find that 
thoughts are suggested which impress upon us most 
startlingly the wonderful nature of the universe, not in 
extent only, but in duration, and in the vitality that per- 
vades its every portion. 



1 34 The Expanse of Heaven. 

A comet is seen in the far distant depths of space as a 
faint apd scarcely discernible speck. It draws nearer and 
nearer with continually increasing velocity, growing con- 
tinually larger and brighter. Faster and faster it rushes 
on until it makes its nearest approach to our sun, and 
then, sweeping around him, it p begins its long return 
voyage into infinite space. As it recedes it grows fainter 
and fainter, until at length it passes beyond the range of 
the most powerful telescopes made by man, and is seen no 
more. It has been seen for the first and last time by the 
generation of men to whom it has displayed its glories. 
It has been seen for the first and last time by the race of 
man itself. Nay more, according to the calculations made 
by astronomers, the comet has made its first and last visit 
to the solar system. Of all comets this cannot, indeed, 
be affirmed ; but there are some whose motions will bear 
no other interpretation. 

And now, what meaning are we to attach to a visit 
such as this ? Whether we trace back the comet's past 
history so far as the imagination or the reason can disclose 
it to us, or whether we follow its future fate, we are 
alike appalled by the stupendous time-intervals which are 
revealed to us. 

Whence came the comet ? Trace back its path, and 
we find no place from which it could have started on its 
course until we consider the stars in the region of the 
heavens whence the comet appeared to travel. It would 
be idle to select any star in particular in that region as 



Visitants from the Star Depths. 135 

probably marking the spot whence the comet started. 
But suppose we take the brightest, some leading orb, 
lying at a distance not absolutely immeasurable by man, 
like the distances of all the millions on millions of stars, 
except some ten or twelve ; suppose even that the course 
of that comet as it approached was such that it might 
have come from the star Alpha Centauri, which, so far as 
is known, is the nearest of all in the heavens ; then, at a 
moderate computation, the journey from the neighbour- 
hood of that star has not occupied less than eight million 
years. 1 

1 The calculation is not altogether simple. Nevertheless, I briefly 
sketch a process of calculation which, though not exact, yet suffices to show 
the order of time-intervals in question in this matter. I assume the mass 
of Alpha Centauri to be four times the sun's — which corresponds with the 
observed brightness of the star, our only means of guessing at its volume 
and mass. I take its distance as exceeding the sun's 210,000 times ; and I 
divide this distance into two parts, one 70,000 times the sunie distance, and 
the other therefore 140,000 times the sun's distance. The smaller distance 
being taken nearest to the sun, it follows from the law according to which 
attraction diminishes with distance, that a particle placed at the point 
separating the two unequal distances is equally attracted by the sun on one 
side and the star on the other. Then I have only to calculate how long it 
would take in passing from the star to that point under the star's influence 
alone, and from that point to the sun under the sun's influence alone, to 
have a rough approximation to the time occupied in the entire journey — an 
approximation certainly not far from the truth, since in the mid-spaces the 
attractions of the two orbs have counterpoising influences, and it the sun 
helps the particle in retreating from the star, the star retards the particle 
as it draws onwards towards the sun. Now, it is easy to find how long a 
particle would take in falling to the sun from a distance 70,000 times 
greater than the earth's. For by Kepler's third law, described in the last 
paper, we have only to multiply 35,000 into itself twice, and to take the 
square root of the result, to get the period of a body moving in any orbit 
whose mean distance is 35,000 times the earth's ; and we get in this way 



136 The Expanse of Heaven. 

Here is a consideration so stupendous that we may 
well pause before accepting it. Let us see whether there 
is any way of escape from it. It appears to me that we 
only come upon greater wonders in endeavouring to avoid 
this one. Suppose we assume that astronomers have been 
mistaken in those cases where they have imagined that 
comets come from the star depths. The observations 
required to be made are, it is true, somewhat delicate, 
and a very slight error of observation applied to a comet 
which really travels in a closed orbit around the sun — a 
very large and eccentric orbit — in a period of two or three 
thousand years, might lead to the mistake of supposing 
that the comet came from interstellar space after a journey 
millions of years in duration. The behaviour of the 
comet, while in our neighbourhood — that is, while it con- 
tinued visible — would be almost exactly the same on either 
supposition. But we gain very little by supposing that 
the comet travels in a long oval. For of all the perplexing 
questions which the astronomer can deal with there is 

6,550,000 years, half of which is the period occupied in falling 70,000 
miles. Here at once we have more than Z\ millions. And for the body 
falling to the star from a distance of 140,000 times the distance separating 
the sun from us, we have an equally simple process, so soon as we have 
noted that owing to the greater mass of the star, a body would only occupy 
half a year in completing an orbit as large as our earth's. We multiply 
70,000 then twice into itself, getting 343,000,000,000,000, and taking (very 
roughly) the square root of this we get 18,600,000, one-half of which gives 
the number of half-years in the fall to Alpha Centauri, so that we get 
4.650,000 years. Adding this to the other period, we get close on eight 
millions of years for the total period occupied by a body in travelling from 
Alpha Centauri to the sun. 



Visitants from the Star Depths. 137 

none more perplexing than the question how comets come 
to travel in closed paths around the sun. That when 
once introduced into such paths they should continue to 
traverse them is easily explained ; but how they enter on 
those paths is a mystery of mysteries, unless we assume, 
as nearly ail astronomers do assume, that comets arriving 
from the interstellar spaces have been so disturbed by the 
attracting influence of some planet as to be forced to 
travel on a closed path. 

We know that Jupiter and Saturn, or the less but still 
giant planets, Uranus and Neptune, have power enough 
so to disturb the motion of an arriving comet, passing- 
near enough to one of these massive orbs ; and we know 
of no other force which could possibly have led to such a 
result : so that this interpretation may be regarded as the 
only explanation which is sanctioned by scientific evidence. 
But then it has simply brought back our difficulty. If 
comets arriving from the interplanetary spaces have been 
thus captured, we still have their journey through those 
spaces to perplex and bewilder us by the stupendous time- 
intervals which they require. 

We may be stopped indeed at the threshold of the 
enquiry by the suggestion that so many thousands of 
years ago the comets were launched upon the paths 
which they are now pursuing, and at such distances from 
the sun as to come into view at their respective times. 
But I may be permitted, I trust, to reject altogether 
such a solution as this, not assuredly because I question 



138 The Expanse of Heaven. 

the Creator's power so to arrange matters if it had pleased 
Him, but because it is rendered manifest by the most 
certain scientific evidence that this has not been the 
Creator's pleasure, that, on the contrary, He has chosen 
to work all things by law. It is indeed only because 
this is so that science has any power to ascertain the 
meaning of processes going on around us. It is by the 
recognition of law in the universe that we are led from 
' nature up to nature's Grod,' and they err who would stay 
the researches which lead to the discovery of the laws of 
the universe, by the simple explanation that 'God so 
willed.' That He did so is certain ; but science is not 
therefore to be checked in its enquiries, as though there 
were fear of her discovering too much. The time has 
not yet come, nor is it likely to come, when science need 
take her shoes from off her feet, because of her too near 
approach to the great First Cause, and because in that 
sense the ground on which she stands is holy ground. 
She stands on holy ground now, and has always so stood, 
because she deals with the ways and works of the Creator. 
But she approaches no nearer to the First Cause in enquir- 
ing into the birth of the solar system than in watching 
the growth of an ephemeron. 

And in truth the subject we are upon touches very 
closely on the question of the origin of our solar system. 
If we deal with comets and meteor-systems as visitants 
from stellar space, we are at once brought into the 
presence of time-intervals so vast as to lead us to epochs 



Visitants from the Star Depths. 139 

when our solar system was in its infancy. The eight 
millions of years I spoke of just now form but the unit 
of time-measurement — that long interval simply ' counts 
one ' in the working of the mighty machine. I took the 
shortest comet-journey, and I took but one journey; but 
according to all reasonable probability not one such 
journey, but thousands, must have elapsed since the 
time when — by whatever process — any given comet was 
first formed. We trace back a comet to the star region 
it came from, as if with the expectation of finding there 
its birth-place ; but from our sun that comet starts on a 
journey which will carry it to another star region, and 
there it will arrive millions of years hence to arouse 
speculation in the inhabitants of other worlds. Why 
should we regard the last known journey of a comet as 
the first it has ever undertaken ? It is as though the 
ephemeron should regard the only day of its short life 
as the first day which had dawned upon the universe. 

But there is a way of viewing this subject which 
leads us at once either to the conclusion just indicated 
or to another equally wonderful conclusion based on the 
soundest principles of probability. Either a comet which 
reaches us from the interstellar spaces has made but one 
journey, or it has made many, flitting from star to star 
in journeys lasting millions of years. If we take the 
last view we begin to perceive by what stupendous time- 
intervals we must measure the duration of the universe. 
But if we take the other, what opinion must we form 



140 The Expanse of Heaven. 

of the immense number of cometic voyages through space, 
when our sun, one amongst millions of millions of suns, 
is visited by so many comets, that Kepler (before the 
telescope had shown the real wealth of comet-matter) 
said that the comets of the solar system must be as the 
fish of the sea for multitude ? Every comet reaching our 
system indicates the existence of comets reaching or 
voyaging towards other systems than ours. We must 
picture the interstellar spaces, which seem wholly un- 
occupied, as in reality tenanted by millions of comets 
for each one of the millions on millions of suns. This 
opinion, indeed, is forced upon us whatsoever view we take 
as to the past history of individual comets. A wonderful 
wealth of matter is thus displayed to us. The whole 
universe is presented as a scene of amazingly complex 
activity ; and to the wonder caused by its infinite ex- 
tent and by the vastness of the orbs which people it, 
there are added the thoughts suggested by the amazing 
voyages which the messengers, as it were, from one 
scheme to another are continually making, and by the 
enormous duration of each single voyage. 

But we have still to consider whence comets come. 
We may trace them through voyage after voyage, but 
that does not bring us to their starting-place. We have 
still to enquire how these strange objects came into exis- 
tence. The enquiry may not indeed be successful, since 
it carries us back to epochs so remote that we may well 
shrink from endeavouring to ascertain what then was 



Visitants from the Star Dep ths. 141 

taking place. Nevertheless, modern science teaches us 
this lesson above all others, that there is nothing old as 
there is nothing new in the universe — that is, that no 
process or state is completely passed, and that no process 
or state now appears for the first time. We will then, in 
another chapter, make a survey of the domain of science, 
' bringing forth things old and new ' for comparison with 
what is known about comets, in order that, if it be possible, 
we may form some idea of the origin of these mysterious 
objects. It may be that we shall find evidence not al- 
together indistinct or unsatisfactory to show that in our 
time and, as it were, under our very eyes comets are 
being brought into existence. Need it be said that if 
this is so, it is to our sun that we shall have to look for 
the processes by which comets are being generated, and 
the materials from which they are being formed ? 



142 The Expanse of Heaven. 



WHENCE COME THE COMETS'? 

What I propose to say in this chapter will probably 
surprise many readers of these pages. It may seem to 
them that the ideas I am about to suggest are too wild 
and fanciful for acceptance. Yet before our enquiry 
begins let us recall to mind the wonderful and mysterious 
facts which have been learned respecting comets, and 
remember that the real explanation of those facts cannot 
but be surprising. Here are these amazing objects often 
exceeding the sun himself many times in size, spreading 
their huge tails over distances measured by millions of 
miles, undergoing the most wonderful changes of shape 
and dimensions, actuated apparently by forces quite 
different in their nature from the force of gravity and far 
more potent in their action, travelling from the inter- 
stellar spaces after voyages of incalculable duration, and 
lastly — most wonderful of all perhaps — returning into 
those far-distant spaces after subserving no useful 
purpose, so far as can be perceived, in the economy of our 
solar system. What can these objects be but wonderful? 
What theory can explain them but one that is as wonder- 
ful in its nature as the objects it is to account for ? We 



Whence Come the Comets? 143 

are in the presence of stupendous facts, and we must not 
therefore be surprised if bold and startling ideas are sug- 
gested in explanation of those facts. 

Two circumstances have recently aided speculation in 
this difficult and perplexing subject. One is the recogni- 
tion, by means of the spectroscope, of the gaseity of the 
head and coma (or hair) of comets. The other is the 
discovery of an association between comets and meteor- 
systems. On the first fact I shall say little, because it 
rather promises future explanation than in itself affords 
sufficient evidence on which to base any opinion respecting 
comets. Doubtless when some splendid comet — like that 
with the aigrette-plume in 1858, known as Donati's, and 
the wonderful object which in the summer of 1861 shone 
for a few days above the horizon during the morning 
hours — shall have been subjected to careful spectroscopic 
analysis, we shall begin to know something respecting the 
actual structure and condition of cometic appendages. 
But for the present the most effective piece of knowledge 
in our possession is that which indicates a connection 
between meteors and comets. 

Briefly stated, the fact — now perfectly demonstrated — 
is this : The only meteor-systems whose paths have been 
recognised are found to travel in the track or orbit of 
known comets. We cannot tell quite certainly what may 
be the nature of the connection thus indicated ; but it 
would seem to be tolerably obvious that the meteors or 
falling stars which are seen for a few brief moments as 



144 2^* Expanse of Heaven. 

they are fired during their rush through our upper air are 
bodies scattered on the track of comets by some process of 
dispersion the nature of which may one day be ascertained. 
And this view seems to be confirmed by Sir John Her- 
schel's observations of the comet of 1862, which not only 
showed the very kind of appearances we should expect on 
this theory, but is otherwise remarkable as being the only 
bright comet yet unquestionably associated with one of 
our recognised meteor-systems — it is 'the parent comet, 
in fact, of the famous August meteors, called also the 
' Perseids,' and sometimes the 6 Tears of St. Lawrence.' 

Now, Sir John Herschel, before it had been demon- 
strated that the comet is thus connected with the August 
meteors, recorded the following observations which he had 
made upon it : — c The phenomena exhibited by its nucleus 
and head were peculiarly interesting and instructive, it 
being only on very rare occasions that a comet can be 
closely inspected in the very crisis of its fate, so that we 
can witness the actual effect of the sun's rays upon it. In 
this case the pouring forth of the cometic matter from the 
singularly bright and highly condensed nucleus took 
place in a single compact stream, which, after attaining a 
short distance, equal to rather less than a diameter of the 
nucleus itself, was so suddenly broken up and dispersed 
as to give on the first inspection the impression of a 
double nucleus. The direction of the jet varied consider- 
ably from day to day, but always declined more or less 
from the exact direction from the sun.' It appears clear 



WJience Come the Comets ? 145 

that there was here a process of raising up, as it were, of 
cometic matter from the head or nucleus, under the sun's 
influence, and that then this matter was swept away as if 
by a repulsive influence exerted upon it by the sun, the 
rate of this repulsion being such that the direction of the 
stream of repelled matter regarded as a whole did not 
lie exactly from the sun, any more than the stream of 
smoke from the funnel of a moving steamer lies as a 
whole in the direction in which the wind is blowing. 

But the special point for our consideration is that 
meteors follow and are obviously connected with comets. 
Now, we cannot examine meteors very well, because they 
never fall to the ground. The spectroscope has been 
applied to them as they have shot across the sky, but the 
attempt is like trying to shoot a bird with a single bullet, 
and the resulting observations are scarcely to be relied 
on. There is a way, however, of ascertaining the pro- 
bable nature of meteors ; because they obviously belong to 
the same class as those masses of matter called aerolites 
which sometimes fall upon the earth from out of the 
interplanetary spaces. These masses can be analysed, 
chemically, microscopically, and otherwise, and so we can 
learn something not merely of their present structure, but 
of their past history. 

Now, the result of such enquiry is very curious. Sorby 
of Sheffield, the eminent mineralogist and microscopist, 
found, nine or ten years ago, that meteoric masses have 
been exposed to processes somewhat resembling those to 



1 46 The Expanse of Heaven. 

which matter is subjected in the great furnaces of Sheffield. 
Here is his account of the matter : — Originally the 
material of aerolites was 'in a state of fusion; and the 
most remote condition of which we have any' positive 
evidence was that of small, detached, melted globules, the 
formation of which cannot be explained in a satisfactory 
manner, except by supposing that their constituents were 
originally in a state of vapour as they ' (that is, the same 
constituent elements) ' now exist in the atmosphere of the 
sun ; and on the temperature becoming lower condensed 
into these ultimate cosmical particles. These afterwards 
collected into larger masses, which have been variously 
changed by subsequent action, and broken up by repeated 
mutual impact, and often again collected together and 
solidified.' This would clearly suggest that these meteoric 
masses were originally expelled either from the sun or 
from one of his fellow suns the stars, or else that we must 
look back to some long past epoch in the history of the 
universe when a true chaos prevailed, regarding meteorites 
as the fragments left from the time of chaos. Let us see 
what the chemical analysis of meteorites may suggest as 
the more probable of these views. 

The chemical evidence is singularly decisive. Pro- 
fessor Graham, the late Master of the Mint, and one of 
the greatest chemists of our day, examined the iron of an 
aerolite called the Lenarto Meteor from the place where it 
fell. He tested it with special reference to the quantity 
of hydrogen contained in it ; for hydrogen and other gases 



Whence Come the Comets ? 147 

can be occluded, as it is called, or as it were closed in, 
within the substance of iron. Now, observe what he says 
about the iron of this meteor : — c It has been found diffi- 
cult to impregnate malleable iron with more than an 
equal volume of hydrogen under the pressure of our atmo- 
sphere. Now, the meteoric iron (this Lenarto iron is 
remarkably pure and malleable) gave up about three times 
that amount without being fully exhausted. The inference 
is that the meteorite had been extruded from a dense 
atmosphere of hydrogen gas, for which we must look 
beyond the light cometary matter floating about within 
the limits of our solar system.' . . . « Hydrogen has been 
recognised by the spectrum analysis of the light of the 
fixed stars by Messrs. Huggins and Miller. The same 
gas constitutes, according to the wide researches of Father 
Secchi, the principal element of a numerous class of stars, 
of which Alpha Lyrse (the leading brilliant of the Lyre) 
is the type. The iron of Lenarto has no doubt come from 
such an atmosphere, in which hydrogen greatly prevailed. 
This meteorite may be looked upon as holding im- 
prisoned within it, and bearing to us, the hydrogen of the 
stars.' 

We are led then to the startling conclusion that comets 
(for what applies to the meteoric trains must needs apply 
to the comets whence those trains proceed) have been 
expelled either from our sun or from one or .other of the 
stars. We may dismiss the sun from consideration, so far 
as most of our cometic visitors are concerned, simply 



14-3 The Expanse of Heaven. 

because any matter he flung forth would either travel for 
ever away from him to visit other systems, or if not 
expelled with sufficient force for that, would return after 
a journey of greater or less length to the globe of the sun 
whence it had been projected. The fact is that most of 
the comets expelled from our sun would visit other solar 
systems, while our solar system would be visited by stray 
comets, now from one star, now from another, 

I might pause at this stage to enquire into the singu- 
larly interesting evidence which our sim himself affords 
as to the projectile power which he possesses. I might 
describe processes of solar eruption, actually witnessed and 
watched by astronomers, in which a velocity of ejection 
amply competent to carry matter for ever away from the 
sun was undoubtedly produced by solar volcanic forces. 
But such an enquiry would require an essay to itself, and 
I hope some day to be able to take up that special subject. 
In this place, let it suffice to say that the sun certainly 
possesses power to eject material from his interior, apart 
from that strange repulsive power — far more powerful 
than his attractive energy — which he exerts on the sub- 
stance of comets' tails. And what is true of the sun may 
be regarded as true of each star, since we know that 
every star is a sun, and that many, if not most, stars are 
far mightier suns than ours. 

But now a very curious consideration presents itself. 
Supposing that the large comets which visit our system 
were originally expelled from some one or other of the 



Whence Come the Comets? 149 

suns which people space, it must have been an amazingly 
long time ago that any such comet first came into ex- 
istence. I showed in my last essay that eight million 
years would be the shortest time in which any comet 
could traverse the space separating our system from the 
nearest star. And then it must be regarded as altogether 
unlikely that a comet has made only one interstellar 
journey before visiting us. Far more probably every 
comet has made many journeys, flitting, as I have said, 
from star to star in journeys, each lasting millions of 
y^ars ; and we may say that certainly some comets have 
done so. Now, the stars are not unchangeable. Our own 
sun is undergoing continual changes, and probably will 
die out, and, as a sun, cease to exist, before many millions 
of years have passed, perhaps before many thousands have 
passed. It is also believed by astronomers that not many 
millions of years ago our sun was in a condition quite 
unlike that in which he at present exists. So that when 
some at least of the large comets which have visited our 
system began their being, our sun in all probability was 
not the sun he now is. He was probably larger and more 
nebulous, but less massive ; he was younger and more 
active, but less powerful ; the scheme over which he now 
rules was as yet unformed ; the whole planetary system 
was quite unlike the scheme we now recognise. 

But if this was the case with our sun and his system, 
doubtless it was the case also with most of the suns we 
call stars. We must assume, then, that either the large 



1 50 The Expanse of Heaven. 

comets we have seen came some of them at least from suns 
in a condition quite unlike that of our sun as he now is, 
or else that the sifias which in the far-off ages expelled 
those comets have long since ceased to be suns. Thus 
we either look back to a distant time when the sidereal 
universe was full of younger suns ruling over systems 
still incomplete, or else the eye of reason reveals to us 
countless invisible orbs, which once were suns, still peopling 
the realms of space, but no longer affording light and heat 
and life to the schemes which circle round them. Or we 
may adopt the inference, which perhaps some will consider 
more probable than either, that both views are just ; in 
which case we must assume that even now, at this very 
time, there exist all orders of suns within the sidereal 
universe — suns still growing ; suns ruling over schemes 
already formed around them ; and, lastly, dead and used- 
up suns, waiting, as it were, for some future change, by 
which they will be restored to activity and usefulness. 

But may we not reasonably apply these considerations 
to the minor system, of which the planets are the members? 
If within the star depths we recognise, at least with 
the eye of reason, these various states of being, may it 
not be that within the planetary scheme like varieties 
exist ? We are too apt to consider that a dull uniformity 
pervades those regions which we have not explored ; and 
though the study of our own domain has revealed an in- 
exhaustible variety of nature, condition, and structure, we 
are unwilling to extend the lesson to the spaces around us. 



Whence Come the Comets ? 151 

We look on the stars as suns like our own, on the planets 
as orbs like our earth, on their satellites as moons like 
ours ; and we regard the ring of Saturn with wonder, 
because we know of nothing wherewith to compare it. 
But may we not believe that the wonderful variety we 
recognise among terrestrial phenomena characterises the 
planetary scheme, and in a yet greater degree the amazing 
system of which our sun is but an unimportant member ? 



152 The Expanse of Heaven. 



THE COMET FAMILIES OF THE GIANT 
PLANETS. 

I ha ye already spoken in a previous article l of the 
comet called Biela's — and sometimes the Double Comet, 
or the Lost Comet, because it had first divided into two, 
and eventually vanished altogether away. I have now to 
consider the class of comets to which Biela's belonged — 
the comets of short period. In this class may be 
included all those which have been watched at two or 
. three returns to our neighbourhood, so that Halley's 
comet, with its period of about seventy years, is included 
in the class, while, on the other hand, the periods of such 
comets range down to the short interval of three and 
one-third years, recognised in the case of Encke's comet. 
I do not propose, however, to enter into the history of 
any of these bodies. My special object is to discuss the 
relations they present in connection with the meteor- 
systems respecting which I have spoken in my last 
article. 

It will be remembered that we were led to the 
conclusion that the great comets, as well as the great 

1 See p. 124, 'The Lost Comet' 



The Comet Families of the Giant Planets. 153 

meteoric masses which from time to time fall upon the 
earth, were originally expelled from the stars. Now it 
might seem at a first view reasonable to conclude that 
the small comets also, and the meteor-systems which 
follow in their track, had a similar origin. For in great 
volcanic explosions on our own earth large masses of rock 
and other matter are accompanied by flights of smaller 
missiles, while sometimes the expulsion of large masses 
ceases for a while, and showers of scoriae and cinders are 
alone expelled. If we assume that the eruptions taking 
place in suns are like terrestrial eruptions in this par- 
ticular respect, so that now large masses, and now flights 
of small masses are ejected, we should find the smaller 
comets and their meteor-trains as readily explained as 
the large comets and the great aerolites which probably 
follow in their track. 

But there are certain difficulties in the way of this 
explanation. 

The comets of short period follow orbits which on the 
one hand do not pass near to the sun, while on the other, 
being closed curves, they necessarily differ altogether in 
shape from the paths pursued by bodies arriving from inter- 
stellar space. These comets, then, cannot possibly have 
been expelled from the sun, for matter expelled from the 
sun would either pass away from him or return to him, 
.moving very nearly in a straight course. If we assume 
that these comets were expelled from stars, we have to 
explain how it is that their paths are now so differently 



154 The Expanse of Heaven. 

shaped from those they would have had on first reaching 
our system after their journey through the interstellar 
depths. 

The ordinary explanation of this circumstance is, that 
one or other of the giant planets — Jupiter, Saturn, 
Uranus, and Neptune — has disturbed one of these comets 
as it arrived after its interstellar journey, and has 
compelled it to take up the orbit in which it at present 
travels. If a comet were travelling towards the sun on 
such a course as to pass very close to Jupiter, it would be 
for a time chiefly under the influence of Jupiter's attrac- 
tion, and its path might be so changed, and its velocity 
so reduced, that thereafter it would travel on a closed 
curve around the sun. And so with the other planets just 
named. Now, there is a circumstance in the movements 
of the comets of short period which accords well with this 
explanation. If a comet were at any time so near to the 
planet Jupiter, let us say, as to be treated in the way 
described, the future path of the comet would necessarily 
pass through the spot where the disturbance took place ; 
and although in the course of many years the comet's 
path might be considerably changed, yet a part of the 
path would always pass somewhat near to the orbit of 
Jupiter. And in point of fact this peculiarity is recog- 
nised in a more or less marked degree with all the comets 
of short period. Their paths so cling, as it were, about 
the paths of th^ giant planets, that I long since gave to 
those thus related to Jupiter the title of c Jupiter's comet 



The Comet Families of the Giant Planets. 155 

family,' -while Saturn, Uranus, and Neptune each have 
their dependent comets, those of Neptune forming a 
peculiarly symmetrical family. 

But there is one consideration which renders it 
difficult to suppose that all these comets were thus 
gathered in from the interstellar spaces by the attracting 
energy of the giant planets. For any planet — even the 
mighty Jupiter — to capture a comet, the comet must 
pas£ very near to the planet. For a short time the 
comet must be more strongly controlled by the planet 
than by the sun; and this requires that a comet should 
pass nearer to the planet than its own satellites. Now, if 
we try to picture the circumstances under which a comet 
would arrive from outer space, we readily see that the 
chances are many millions to one against this happening. 
The span of Jupiter's orbit amounts to about nine hundred 
millions of miles, and an arriving comet would be unlikely 
to approach the sun on the level of Jupiter's path ; it 
might arrive from above or below, and at any degree of 
slope. The orbit of Saturn is twice as wide as that of 
Jupiter ; that of Uranus is twice as wide, and that of 
Neptune thrice as wide as the orbit of Saturn. Compared 
with these enormous distances, the distances within which 
a comet must approach these planets, in order to be 
brought into subjection and compelled to travel in a 
closed orbit round the sun, are altogether minute. 

Either, then, we must assume that in the case of every 
captured comet there has been a most wonderful coin- 



J 5 6 The Expanse of Heaven. 

eidence, or else that many millions of comets have arrived 
for each one that has been captured. And as it is certain 
that for every known comet of short period there must be 
hundreds or thousands unknown, we see that the latter 
supposition involves very remarkable ideas as to the 
wealth of cometic matter in the universe. Then we have 
the same enormous time-intervals to consider in the case 
of these small comets as in the case of the large comets 
already discussed, with the additional time required to 
reduce the smaller orbits to their present shape. 

It is worth enquiring, therefore, whether there is no 
simple explanation — not, indeed, that we can hope to find 
any interpretation which is not of a surprising and even 
startling nature, but that perhaps one may be found which 
would give a more satisfactory and systematic account of 
the comets of short period. 

Since these comets are associated in so peculiar a 
manner with the giant planets of the solar system, may it 
not be that they bear a relation to these planets somewhat 
resembling that which the large comets bear to the suns 
which people space ? As the large comets would seem to 
have been expelled from these suns, may not the small 
comets have been expelled from the giant planets ? We 
need not necessarily assume that these giant planets are 
still in the active and sunlike state necessary, we may sup- 
pose, for the expulsion of comets. 3?ven this assumption 
is not altogether without evidence in its favour; and, 
indeed, I have long since been led, by evidence of another 



The Comet Families of the Giant Planets. 157 

kind, to the conclusion that Jupiter and Saturn are secon- 
dary suns to the schemes of secondary planets which circle 
around them. But it may be on the whole safer to assume 
that the birth of the comet families of the giant planets 
took place in far distant eras, when these orbs were not 
merely as now instinct with an intense heat, but also aglow 
with light, so as to present, when viewed from other 
systems, the aspect which the small companions of un- 
equal double stars present to our telescopists. Astrono- 
mers have long since seen reason for believing that 
all the planets, including our own earth, were once 
luminous with intensity of heat, and the giant planets, 
. when in that condition, were probably comparable as light- 
givers to many of the minor suns of our galaxy. There 
seems nothing unreasonable, therefore, in the supposition 
that as the leading suns .have expelled the large comets 
now followed by trains of meteorites, so these minor suns 
— Jupiter, Saturn, Uranus, and Neptune — ejected the 
small comets followed by flights of relatively minute 
meteors. 

Now, it happens that there is one piece of evidence 
which seems strikingly to favour the theory here advanced. 
It is clear that captured comets would be as likely to be 
sent round the sun on their new orbit in one direction as 
another — advancing or retrograde— that is, in the same 
direction that the planets travel in, or in the opposite 
direction. But comets expelled from a planet would 
partake in the motion of the planet, and this motion, 



158 The Expanse of Heaven. 

though it would be combined with the motion of ejection, 
would probably leave a balance of advancing motion. 
Supposing a person in a rapidly advancing open carriage 
were to throw stones in all directions around him, is it 
not clear that more of these would travel forwards than 
backwards, simply because the forward motion of the 
carriage would always be added to the motion imparted to 
the stone ? If the open carriage belonged to a railway 
train moving at express speed, all the stones would move 
forward, even those which were flung directly backward, 
as respected the train. 1 Applying the principle here 
illustrated to the case of the comet families, we see that 
if they were ejected from the planets with which they 
are respectively associated, we might expect to find the 
greater number travelling the same way round the sun as 
the planets. Moreover, we see that this peculiarity 
would be more marked the greater the velocity of the 
parent comet, and that probably the comets depending on 
Jupiter, the most swiftly travelling of the giant planets, 
would all travel forwards. Now, this is precisely the state 
of the case. Far the greater number of the comets of short 
period travel advancingly, or like the planets ; and while 
some few of those dependent on the outer planets, Neptune 
and Uranus, travel in a retrograde manner, none of those 
dependent on Jupiter so travel. 

Yet another piece of evidence. For the same reason 

1 The experiment hero indicated is not one that any reader should at- 
tempt to carry out in a practical manner. 



The Comet Families of the Giant Planets. 159 

that ejected comets would for the most part travel forwards, 
there would be a tendency among their orbits to lie near 
the level of the planetary orbits. At any rate, we might 
expect to find such a tendency among those depending on 
Jupiter. The case is precisely like that just considered, 
and can be illustrated in the same way. If stones were 
flung in all directions from a very swiftly moving train, 1 
they would not only all move forwards, but there would 
be a tendency to horizontal motion, simply because 
every stone would partake in the horizontal motion of the 
train. 

Even a stone thrown vertically upwards from the 
train would move slantwise with respect to the earth. 
Now, here again the facts of the case favour the strange 
theory I am dealing with. The comets which come from 
interstellar space show every variety of inclination to the 
general level of the planetary motions. Those depending 
on the outer planets are, for the most part, not very 
greatly inclined to that level. Those attending on Jupiter 
do not include one case of great inclination, and are for 
the most part very little inclined. 

There is . not much evidence, it may be admitted, in 
favour of the theory we are considering. Still the balance 
of evidence favours this theory rather than the theory 
that the comets of short period have been in the main 

1 I suppose, at least, that a stone cannot be flung with the speed of an 
express train ; but I have no certain knowledge as to the greatest velocity 
which an expert thrower can impart to a stone flung in the usual way. 



1 60 The Expanse of Heaven. 

drawn from the interstellar spaces. And so far as can 
be judged no other theory than these two can be ima- 
gined. 

Now, whether we regard the giant planets as still en- 
gaged in the work of comet ejection or suppose that they 
have long since ceased to possess the powers necessary for 
that work, we have alike a curious subject of contempla- 
tion. In one case we see that a strange variety exists 
within the planetary system, where our earth and her 
fellow minor planets are fit abodes for life, while the 
giant planets are in a state of intense activity. In the 
other we see that a strange difference exists between the 
present condition of the outer planets and their condition 
in long past ages. I do not know which thought is the 
more suggestive; but I may note in passing that both 
thoughts may be admitted at the same time, and that in 
fact it is altogether more probable that both are just than 
that one must be rejected in favour of the other. Truly, 
when we view our solar system in the light of such consi- 
derations as these, we begin to see how much more won- 
derful the planetary scheme is than it has been repre- 
sented in the text books of astronomy. We no longer are 
a uniform system, inert and lifeless, so far at least as life 
is measured by change, but a scheme full of variety, 
instinct with energy and vitality, changed in all parts 
from the condition it once had, changing in all parts 
towards new conditions — a living, growing, developing 
system, a fit world of life to be ruled over by the mighty, 



The Comet Families of the Giant Planets. i6r 

ever active sun. As we contemplate these wonders, we 
seem to find a new meaning in the words of the Psalmist, 
1 The heavens declare the glory of God ; and the firma- 
ment sheweth His handywork. There is neither speech 
nor language, but their voices are heard among them.' 



1 6 2 The Expanse of Heaven. 



THE EARTH'S JOURNEY THROUGH SHOWERS. 

There are some facts in astronomy the real significance 
of which scarcely strikes us as they are ordinarily pre- 
sented. We note with more or less interest, perhaps with 
wonder, a series of statements in which great distances 
and large masses are referred to with an imposing array 
of figures, but we fail to recognise adequately what the 
statements mean. This is particularly the case with 
some of the more recent discoveries made by astronomers. 
They are so pregnant with meaning, so stupendous, not only 
in their direct significance, but in the inferences which 
flow from them, that time is required even to view them 
aright, and much more time to realise their full signi- 
ficance. 

Perhaps there is no department of astronomy to which 
these remarks are more strikingly applicable than to 
meteoric astronomy. I have already touched on some of 
the remarkable inferences, as to cosmical relations, which 
may be deduced from recent discoveries respecting 
meteors and meteor-systems. I propose now to touch on 
the subject in its terrestrial aspect: to show what is 



The Ear t lis Journey through Showers. 163 

actually taking place as our earth urges her way on her 
wide orbit round the sun, saluted on all sictes by meteors — 

Pelted with star dust, stoned with meteor balls — 

though not always exposed to meteor showers of equal 
heaviness. 

It is perhaps sufficiently startling to be told at the 
outset that nearly all shooting stars— nine hundred 
and ninety-nine out of every thousand, certainly — are 
missiles which rush towards the earth with a velocity 
far exceeding that of the swiftest cannon-ball. They are 
not missiles which miss their mark. They do not, as was 
once thought, merely graze our atmosphere. They come 
straight towards the earth, and many among them must 
make straight towards living creatures on the earth. And 
though they are for the most part small, they are by no 
means so small as to be unable to destroy life. Their 
swift motions make up for their smallness, and the actual 
momentum of some of the tiniest of these bodies is equi- 
valent to the momentum of a cannon-ball. 

We might afford to make little of the danger (for 
danger there would be but for a circumstance presently to 
be mentioned) were the number of these bodies small. If 
ten or twenty saluted the earth during the twenty-four 
hours, the chance that even in the course of a century any 
living creature would be struck would be small. For the 
earth is large, and living creatures occupy but a small 
portion of its surface. But, I think, many among my 



1 64 The Expanse of Heaven. 

readers have no adequate conception of the enormous 
number of meteors which each year fall upon the earth. A 
million a year would bring some degree of danger. But 
the actual number is far greater. It has been estimated 
by Professor Simon Newcombe, of America, on grounds 
which are perfectly reliable, that including telescopic 
meteors (that is, meteors so small as only to be visible 
when they happen to pass across the field of view of a 
telescope) no less than 146,000 millions of meteoric 
bodies fall each year upon the earth. If one in a 
thousand struck a human being the inhabitants of the 
earth would be decimated in a single year. 

How then is it, it may be asked, that we never hear of 
even an accident from ordinary meteors, though accidents 
from aerolites have not been altogether unknown ? Here 
is this great vessel, the earth, sailing through space, and 
saluted every twenty-four hours by 400 millions of missiles, 
each flying towards her with many times the velocity of 
the swiftest cannon-ball. This goes on by day and by 
night, when living creatures are far from shelter as well as 
when they are protected in their various abodes; and yet 
the inhabitants of earth are perfectly safe from all danger. 
It is not merely that they have been so far fortunate as to 
escape hitherto, but that they really are as safe as though 
the earth were protected by those three-feet armour plates 
which will one day, we are told, defend our floating 
batteries. 

The real protection of the earth is the air which sur- 



The E art lis Journey through Showers. 165 

rounds her. Soft as the air is, the resistance it opposes to 
swift motion is very great. The swifter the motion the 
more effective is the resistance. In the case of the meteoric 
missiles falling on the earth the resistance is so great, 
owing to their enormous velocity, that they are consumed 
and presently vaporised in their rush through the upper 
parts of the air. For the most part they appear to pene- 
trate the air to a depth of about twenty miles below the 
height at which they are first rendered visible by the in- 
tensity of their heat. For they mostly appear when still 
at a height of seventy miles and vanish when at a height of 
about fifty miles. But the actual course they pursue through 
the air is nearly always much longer, because they do not 
descend vertically but aslant. It is easily intelligible that 
the extreme rarity of the air at these heights is compen- 
sated by the vastness of the distance through which the 
meteor travels in a very short time. For most of the 
meteors are travelling through the air, when they begin 
their passage through it, at the rate of twenty or thirty 
miles per second, and though their velocity is much 
reduced in the course of their flight, yet, as everyone 
knows who has seen shooting stars, they execute 
their long flight through the upper air-strata in which 
they are destroyed at a very high velocity, being seldom 
visible more than a few seconds. Thus the air forms a 
perfect protection to our earth. The words of Milton 
respecting the air, although used by him in another sense, 
yet by a happy accident apply with singular fitness to the 



1 66 The Expanse of Heaven. 

services actually rendered by the air according to recent 
astronomical discoveries respecting meteors : — 

God made 
The firmament, expanse of liquid, pure, 
Transparent, elemental air, diffused 
In circuit to the uttermost convex 
Of this great round ; partition firm and sure 

. lest fierce extremes 

Contiguous might distemper the whole frame. 

Nevertheless, although none of the meteors reach the 
surface of the earth in their original solid form, their sub- 
stance must in the long run sink down through the air 
until it settles on the earth. For though they are vapo- 
rised through intensity of heat, yet they can remain in the 
vaporous state but a few seconds, presently changing into 
the form of mere dust by a process of condensation, pre- 
cisely resembling that which changes the invisible vapour 
of water in our air into the form of visible clouds of water 
globules. This meteoric dust being extremely fine must 
sink very slowly, but in the long run every particle of it 
reaches the earth. 

Evidence has been obtained on this point — though 
even without such evidence no doubt could well be enter- 
tained on the subject. Dr. Eeichenbach collected dust 
from the top of a high mountain, which had never been 
touched by spade or pick-axe ; and in analysis he found this 
dust to consist of almost identically the same elements as 
those of which meteoric stones are composed — nickel, cobalt, 
iron, and phosphorus. Dr. Phipson also, in his interesting 



The EartJis Journey through Showers. 167 

work on c Meteors, Aerolites-, and Shooting Stars,' remarks 
that ' when a glass covered with pure glycerine is exposed 
to a strong wind, late in November, it receives a number 
of black angular 'particles, which can be dissolved in 
strong hydrochloric acid, and produce yellow chloride 
of iron upon the glass plate.' 

It is a strange thought that the breath we draw 
contains matter which has circled in the meteoric form 
around the sun, visiting in its course the space where 
Mars and Jupiter, Saturn, Uranus, and Neptune * pursue 
their paths. 

And here the question suggests itself whether the 
supply of meteoric dust is necessary to the well-being 
of the inhabitants of earth. That it is not on the whole 
injurious is manifest, for the supply has continued for 
ages, and will continue for many ages to come. It is not 
at all unlikely that it is to some degree necessary for 
our well-being, though the doses of meteoric matter 
which we receive are altogether infinitesimal. But the 
supply is variable, since sometimes there are showers of 
meteors, while at others there are but a few scattered 
meteors for several days in succession. May it not be 
that meteors in excess are bad for the inhabitants of 
earth? or else (for we have no satisfactory evidence 

1 This applies of course only to certain meteors. Some meteors do not 
travel beyond the path of Jupiter; and probably only a small proportion pass 
beyond the orbit of Neptune. 



1 68 The Expanse of Heaven. 

either way) that a great deficiency in the supply might 
lead to mischief? 

It has been suggested that some of the pestilences 
which history records were produced by meteoric in- 
fluences. It seems tolerably clear that the worst plagues 
were due to the great plague-generator, Uncleanliness. 
But some of the plagues were so sudden in their origin, 
lasted so short a time, and had such singular features, as 
to suggest the idea of extra-terrestrial influences. Amongst 
these may be mentioned the sweating sickness of the 
fifteenth and sixteenth centuries, which wks not only 
characterised by the peculiarities in question, but, by 
its recurrence thrice in forty-six years, has suggested 
the action of a recurrent cause like the return of meteoric 
clusters circling around the sun. 

Note, for instance, Bacon's description of this sickness 
in his Life of Henry the Seventh : — 

' About this time,' he says, speaking of the year 1485, 
6 in autumn, towards the end of September, there began 
& reigned in the city, and other parts of the kingdom, a 
disease then new : which, by the accidents and manner 
thereof, they called the sweating sickness. The disease 
had a swift course, both in the sick body, and in the time 
and period of the lasting thereof; for they that were 
taken with it, upon four and twenty hours escaping, 
were thought almost assured. And as to the time of the 
malice & reign of the disease ere it ceased, it began about 
the one and twentieth of September, & cleared up before 



The Eartlis Joitmey through Showers. 169 

the end of October, insomuch as it was no hindrance to 
the king's coronation which was the last of October ; nor, 
which was more, to the holding of Parliament, which 
began but seven days after. It was a pestilent fever, 
but, as it seemeth, not seated in the veins or humours, 
for that there followed no carbuncle, no purple or livid 
spots, or the like, the mass of the body being not tainted ; 
only a malign vapour flew to the heart and seized the 
vital spirits ; which stirred nature to strive to send it 
forth by an extreme sweat. And it appeared by ex- 
perience that this disease was rather a surprise of nature 
than obstinate to remedies, if it were in time looked into. 
For if the patient were kept in an equal temper, both for 
clothes, fire, & drink, moderately warm, with temperate 
cordials, whereby nature's work were neither irritated by 
heat nor turned back by cold, he commonly recovered. 
But infinite persons died suddenly of it, before the 
manner of the cure and attendance was known. It was 
conceived not to be an epidemic disease, but to proceed 
from a malignity in the constitution of the air, gathered 
by predispositions of seasons ; and the speedy cessation 
declared as much.' 

It certainly seems impossible to conclude certainly 
that the earth's inhabitants are safe from all extra- 
terrestrial influences. When we remember, too, that a 
connection has been traced between comets and meteors, 
we can believe that possibly the fear with which comets 
have been regarded may not be altogether so ill-founded 



1 70 The Expanse of Heaven. 

as astronomers have been led to believe of late years. 
Certainly there is small risk from any effects of collision 
with comets, since we have learned that the mass even 
of the largest comet is inconsiderable. But the inter- 
mixture of cometic matter with the atmosphere of our 
earth might not always be a perfectly innocuous process. 
We do not as yet know what are the gases which are 
the chief constituents of the vaporous parts of comets, 
nor the proportion in which solid and liquid matter may 
be present in the heads and nuclear parts of comets. 
But there are few gases which, added in very large 
quantity to our air, would do no harm; and any con- 
siderable addition of solid matter, first vaporised and 
afterwards settling as a fine dust through the air, might 
severely injure at least those of delicate constitution. 

There are some eventualities, indeed, which are very 
startling to contemplate, yet not altogether inconceivable. 
Suppose, for instance, that a comet composed in the main 
of hydrogen should mix with our air, until the oxygen 
of the air and the hydrogen of the comet were in the 
proportion in which these gases are present (chemically 
combined) in water. Then unless every fire and light 
in the whole earth were extinguished there would be 
a tremendous explosion, followed instantly by a deluge 
of water, and leaving the burnt and drenched earth no 
other atmosphere than the nitrogen now present in the 
air, together with relatively small quantities of deleterious 
vapours. 



The EartJis Journey through Showers. 1 7 1 

We need not greatly trouble ourselves, however, with 
the fear of such a calamity. If hydrogen comets were 
common, the earth would probably have encountered one 
long ago, in which case her condition would certainly 
not be such as it is at present. It is, however, not at 
all improbable that the earth is not merely exposed to 
mischief, but that her inhabitants have actually suffered, 
more or less seriously, at intervals, from the meteoric 
and cometic matter which falls upon her as she journeys 
onward through showers. 1 



1 The medal commemorating the great plague of London, which was 
associated, it will be remembered, with the appearance of a comet, pictures 
the comet as scattering pestilence from its tail. According to this curious 
medal, pestilence was scattered in the form of small pothooks. Defoe's 
remarks about this comet, and the one which appeared a year after, are 
curious : — ' A blazing star or comet appeared/ he says, * for several months 
before the plague, as there did the year after, a little before the fire ; the 
old women and the phlegmatic hypochondriacal part of the other sex, whom 
I could almost call old women too, remarked, especially afterwards, though 
not till both those judgments were over, that these two comets passed 
directly over the city, and that so very near the houses (! !) that it was plain 
they imported something peculiar to the city alone ; and the comet before 
the pestilence was of a faint dull languid colour, and its motion very heavy 
and slow ; but that the comet before the fire was bright and sparkling, or 
as others said, flaming, and its motion swift and furious : and that accord- 
ingly one foretold a heavy judgment, slow but severe, terrible and frightful 
as was the plague ; but the other foretold a stroke sudden, swift, and fiery, 
as was the conflagration ; nay, so particular some people were, that as they 
looked upon that comet preceding the fire, they fancied they not only saw it 
pass swiftly and fiercely, and could perceive the motion with their eye, but 
even they heard it, that it made a rushing mighty noise, fierce and terrible, 
though at a distance and but just perceivable. I saw both these stars, and 
I must confess, had had so much of the common notion of such things in 
my head, that I was apt to look upon them as the forerunners and warnings 
of God's judgments, and especially when the plague had followed the first, I 



172 The Expanse of Heaven. 

In my two next chapters I shall consider how the 
earth and other planets may be regarded as growing 
under the continual downfall of meteoric matter; and 
how, although this growth must be regarded as exceed- 
ingly slow in these our times, yet in past ages the 
members of the solar system, and the sun himself, must 
have grown appreciably in volume and mass under the 
continual influx of meteoric matter, 

yet saw another of the like kind, I could not but say, God had not yet 
sufficiently scourged the city.' 



HOW THE PLANETS GREW. 



In considering the wonderful processes which are taking 
place within the limits of the solar system, and still more 
in endeavouring to trace back the course of events during 
former ages, we find ourselves surrounded by a hundred 
sources of perplexity. Nor is it to be expected, perhaps, 
that we should be able, either now or at any future time, 
to form clear ideas on a subject so involved in mystery. 
The powers of man — I am speaking of the race, not 
of individual men — are wonderful. The Almighty has 
enabled them to deal successfully with many problems 
which, even now that they have been solved, seem as 
though they had been placed beyond all reasonable hopes 
of mastery. But it has not been given to man to solve 
all the mysteries that surround him, and it may well be 
questioned whether it will ever be in his power to solve 
that great mystery, the origin of the wonderful scheme of 
worlds of which our earth is a member. 

Yet there are steps which man can fairly hope to make 
on the path leading towards the great secret. There are 



1 74 The Expanse of Heaven. 

processes still taking place which he can gauge and 
measure, thence inferring the probable nature of the 
corresponding processes in long past ages of the world's 
history. There are signs which are full of meaning, 
traces which can be followed for a great way — we do not 
yet know how far. 

It is certainly a legitimate exercise of the powers given 
to man to follow out those paths, whether well marked or 
as yet little trodden, which seem likely to lead to new 
knowledge. We need not be troubled by doubts as to the 
way in which such paths may lead us, so that they really 
lead to the recognition of facts. We may learn many 
things inconsistent, perchance, with our present ideas as 
to the way in which it has pleased the Almighty to 
provide for His worlds. We may have to abandon some 
conceptions which had appeared very accordant with the 
might and wisdom of the Creator. But we may be sure 
of this, that whatever new ideas we may legitimately be 
led to, will prove not less worthy of Him. Increase of 
knowledge of His universe — whether of its various parts 
or of the various periods of its history — will enhance our 
conceptions of His power and wisdom, though still leaving 
those conceptions infinitely poor and feeble compared with 
the reality. 

I make these preliminary remarks, because, strangely 
enough, many persons of religious mind seem afraid to 
enter upon the course here indicated, and follow with 
unwilling footsteps those who try to advance some short 



How the Planets Grew. J75 

distance upon it. Of those who have such fears, the 
believing student of science (that is, of the knowledge of 
God's works) may justly ask the question, ' Why are ye 
so fearful, ye of little faith ? ' 

There are manifest signs in the present configuration 
and motions of the planetary system of a process of 
evolution by which in long past ages it grew to its 
present condition. There is, of course, nothing to prevent 
any man from believing that precisely as the solar system 
is now it was created so many thousands of years ago. 
The Almighty might have chosen that at a certain instant 
Neptune, Uranus, Saturn, and Jupiter — the zone of 
asteroids — and the family of minor planets, to which our 
earth belongs — should come into being, should be set 
revolving each on its proper orbit, and rotating each with 
its due period, should be clothed with atmospheric 
envelopes, diversified with oceans and continents, and in 
fine created just as they at present exist. 

I say there is nothing to prevent anyone from 
adopting this view, because a Being of infinite power could 
have so arranged matters that all the evidence available 
on the subject should be precisely as it now is ; and, as 
we have no record handed down by actual witnesses of the 
earlier history of the solar system, it is impossible to know 
certainly that this was not the actual order of things. 
Noiv, as in the days of Job, no man can answer when the 
questions are asked, < Where wast thou when God laid the 
foundations of the earth ? declare," if thou hast under- 



1 76 The Expanse of Heaven. 

standing. Who hath laid the measures thereof, if thou 
knowest ? Or who hath stretched the line upon it ? ' 

But it is reasonable to study the processes which are 
actually taking place around us, as well as the condition 
of those parts of the universe which we can examine, and 
to infer from such researches whatever is ascertainable as 
to the past history of created things. We may compare 
man's range of research to some region where races of 
shortlived insects have their being, and the processes 
which man can watch to those which take place within 
the cognisance of such creatures, supposing only that they 
had the power to investigate and to reason as man does. 
Let us imagine that such creatures noted the slow 
processes of change taking place in a tree near which they 
lived. To them these processes would seem infinitely 
slow compared with the rate at which ive perceive these 
processes to take place. The growth of a leaf might, 
perhaps, occupy more time than the whole life of one of 
these creatures. Yet, if from one generation to another 
the knowledge gradually acquired were carefully handed 
down, it would be possible to recognise the nature of the 
growth and development of the tree. With further study, 
occupying perhaps the time and labour of several more 
generations, it would be possible to infer something of the 
fixture of the tree, and even perhaps to recognise the fact 
that at some (to them) very far distant epoch the tree 
would decay and perish. 

But with such knowledge would come also the means 



How the Planets Grew. 177 

of inferring what had been the history of that tree during 
periods antecedent to the very existence of their race, and 
whose duration could not but appear to them as practi- 
cally infinite. It might not be given to them to trace 
back the history of that tree to the time when the seed 
from which it sprang began first to germinate. Still less 
might they be able to recognise the law according to 
which tree succeeded tree — one form of the universe (in 
their eyes) succeeding to another form, according to the 
law of being of these tree universes. Their knowledge 
could be carried back to a certain distance, to a period 
infinitely remote to their ideas, but now beyond. It is 
not unlikely that they would regard the beginning of all 
tilings as lying just beyond the limits they were able to 
reach ; and yet in reality, since the next step backwards 
would be but to the falling of a seed upon the earth, 
their conception of creation would be contemptible in the 
eyes of men. 

I think we may very safely carry out investigations 
back as far as we possibly can. We cannot, I conceive, 
go very far ; though we may imagine, if we please, that 
just beyond the period to which we carry back our thoughts 
lies the beginning of all things. Probably — nay, to my 
own mind, certainly — our ideas are as inadequate and 
feeble, compared with the reality, as those which I have 
pictured as the ideas of ephemeral insects. And certainly 
any conception of creation which placed its epoch just 
beyond the limits to which our powers enable us to reach 



1 78 The Expanse of Heaven. 

in our retrospective researches, would appear contemptible 
to beings in existence when the foundations of the universe 
were laid, c when the morning stars sang together, and all 
the sons of God shouted for joy.' 

In my last article I mentioned that the earth is grow- 
ing. Day by day and year by year meteors are falling 
upon the earth, not by hundreds and thousands, but by 
thousands of millions. This process of growth is, however, 
exceedingly slow. Estimated indeed by the actual quan- 
tity of matter falling year by year upon the earth it seems 
like a real appreciable growth. For let us suppose that on 
the average each meteor of more than 140,000 millions 
which fall per annum weighs but a single grain. Then 
the earth's weight is increased each year by 20 millions of 
pounds, or by more than 90,000 tons. Yet this is a mere 
nothing compared with the actual weight of the earth. 
Supposing the matter thus received to be spread uniformly 
over the whole surface of the earth, it would form a layer 
less than the 800,000,000th part of an inch in thickness. 
So that at this rate 400 millions of years must elapse 
before the earth's diameter would be increased a single 
inch. Thus it may fairly be said that though the earth is 
really acquiring new mass year by year, yet she is no 
longer growing appreciably in dimensions. 

We see here a process which may be compared to what 
takes place in a tree when it has acquired its full dimen- 
sions. And as the mere life of a tree no longer growing 
yet teaches us by what processes the tree grew, so I 



How the Planets Grew. 1 79 

conceive that the gathering in of meteoric matter which 
now takes place at so low a rate as to produce no appre- 
ciable groivth yet indicates the nature of the processes by 
which in bygone ages the earth and her fellow-planets 
grew to their present dimensions. The meteors now 
being gathered in are but as a remnant. They are ne- 
cessarily being reduced in number year after year, and we 
have only to look far enough back to recognise a time 
when they were so numerous that their downfall sufficed 
to produce a real and appreciable increase in the bulk of 
the planets. 

I have mentioned certain indications in the solar 
system of past processes of evolution. These are in their 
way as sufficient as the indications afforded by the suc- 
cessive rings in the section of a tree's trunk. Let us 
briefly consider what the solar system thus teaches us 
about its past history. 

All the planets travel the same way round. This is 
true not only of the eight primary planets but of the 
asteroids, now more than a hundred and thirty in number* 
Again, all the secondary planets or satellites travel the 
same way round (this direction of revolution being the 
same as that in which the planets revolve round the sun) 
— except the satellites of Uranus, which, however, can 
hardly be said to have any direction of motion with refe- 
rence to the general level in which the planetary system 
circuits, for they travel in planes nearly square to that 
level. Lastly, as respects direction of motion, all the 



1 80 The Expanse of Heaven. 

planets whose rotation has been observed^ including our 
earth and the moon, and the sun also, rotate on their 
axes in the same direction. It must be understood that 
this direction is one and the same for all these motions — 
the revolutions of the planets around the sun, of the 
satellites round the planets, and of the planets on their 
axes. 1 

Now, there is no reason, in the nature of things, why 
this uniformity of direction should exist. If some planets 
went round one way, and some the other, it would still be 
as well with the solar system as at present. If our moon, 
or the moons of Jupiter or of Saturn, went round the 
other way no harm would follow. If the earth or any 
other planet turned on its axis the other way round, the 
inhabitants would be as well off as they are at present. 
It seems natural to infer that the uniformity is the 
result of some general condition affecting the whole 
scheme from the beginning. Of course we may argue 
that the uniformity exists because God so willed it, pre- 
cisely as our illustrative insects, if they lighted on some 
old tree stump lately sawn, and perceived the circular 
rings in its section, might argue that the shape of these 
was in no way connected with the growth of the tree, but 
that the rings were circular and concentric because the 
Almighty had pleased to create them so. Such reasoning 

1 Looking down on the solar system from the northern side, these 
motions would all be the reverse of that in which the hands of a watch 
move. 



How the Planets Grew. r8 1 

on the part of ephemeral and feeble insects appears ridicu- 
lous in our eyes, who are so long-lived, so strong, and so 
wonderfully knowing. Let us not be too sure, however, 
that we are not falling into a mistake equally ridiculous 
in the eyes of the All-knowing, in regarding the coming 
into being of the solar system as synchronising with the 
beginning of all things. 

If we reject this view as narrowing (preposterously, 
perhaps, if the truth were known) the range of time 
within which created things have existed, we have no 
choice but to regard the observed uniformity as the 
result of the action of some process of evolution, since 
the peculiarity is a most marked one. Setting the 
matter as a question of probabilities, the chances are 
many millions of millions to one against the observed 
state of things, 1 except as the result of express contrivance 
on the one hand or of a uniform process of evolution on 
the other. 

Now, the French astronomer Laplace showed how all 

1 Taking the revolution of the planets in one common direction alone, 
and counting 140 planets (all at present known), the odds against the ob- 
served coincidence of direction are as 2 multiplied into itself 138 times to 
unity (or in technical terms, as 2 raised to the power 139 to unity). (The 
odds are as 2 raised to the power 140 to unity against the planets all going 
round in the actually observed direction, but only one-half this against 
their all going the same way round, that way being indifferent.) Now, 2 
raised to the power 139 is a number of 42 digits, beginning 69,370, &c, 
and the antecedent odds against the observed relation are represented by 
the proportion of this enormous number to unity. 

[Since this was written the 133rd asteroid has been discovered, raising 
the odds to 138,740, &c. (43 digits) to one.] 



1 8 2 The Expaiise of Heaven. 

these motions would have resulted if the solar system had 
once been a great mass of intensely hot vapour turning 
round and round as upon an axis. This whirling mass of 
vapour would contract as it parted with its heat, and, as 
it contracted, would whirl more swiftly. This increase of 
its rotating movement would cause the outer parts to be 
separated, and a ring would be thus thrown off. This 
ring would eventually break up and form a minor vapour 
mass, circling around the remainder of the contracting 
mass. Moreover, Laplace showed that the mass thrown 
off would rotate in the same direction in which it 
revolved. Now, we have only to conceive this process 
repeated several times as the vapour mass continued to 
contract to understand the formation of the primary 
planets. We have only to suppose further that the larger 
vapour masses thrown off, as supposed, themselves con- 
tracted in the same way, and thus formed subordinate 
systems, to understand the existence of satellite systems 
like those circling around Saturn, Jupiter, Uranus, and 
Neptune. A ring such as the ring of asteroids or the 
Saturnian rings would, under exceptional circumstances, 
be formed instead of a single planet or satellite. And 
thus the main features of the solar system are accounted 
for. 

Eut this ingenious theory does not account for some 
peculiarities which are scarcely less remarkable than 
those on which it has been based. In particular it does 
not account for the strange disposition of the masses of 



How the Planets Grew. 183 

the solar system. Why should the inner family consist 
of minor bodies, in the main unattended, while the outer 
consists of giant orbs with extensive families of satellites ? 
Why should the innermost members of the outer family 
of planets be the largest, while just within there lies the 
family of asteroids, not only individually minute, but 
collectively less (as Leverrier has proved) than Mars or 
even Mercury ? Why should the two middle planets of 
the inner family be the largest members of that family ? 
Laplace's theory gives no account of these peculiarities ; 
nor perhaps could it be insisted that these peculiarities 
should be explained : yet, if any other theory should give 
an account of these features, explaining also the features 
which we have seen accounted for, then such theory 
would have a decided advantage over Laplace's. It is to 
be noticed also that Laplace's great nebulous contracting 
mass is a very unsatisfactory conception to begin with. 
No such mass could rotate as a whole. And lastly, 
Laplace's theory does not in any way correspond with 
processes still taking place within the solar system. It 
gives no account of the immense number of meteor 
flights and comets still existing within the solar domain. 

In the next chapter I shall attempt to maintain a 
theory of the evolution of our solar system which has in 
these respects the advantage of Laplace's, and which I 
believe to accord much better, on the whole, with the real 
order of events in the past history of the solar system. 



184 



The Expanse of Heaven. 



II. 



It will be remembered that in my last chapter I 
mentioned the peculiarities of the distribution of the 
masses composing the planetary system as an objection to 
Laplace's theory of the formation of that system. These 
peculiarities have long been recognised as a stumbling- 
block in the way of any uniform theory of growth. Hum- 
boldt (of whom, however, it is necessary to remark that 
he is not of authority as an astronomer) noted long since 
the very peculiar arrangement of the planets as respects 
their dimensions, and specially as respects their mass. I 
propose, briefly, to indicate the evidence on this point. 

First, let us see how the masses are arranged. The 
following table is useful for this purpose : — 





Mass 




Distance from the Sun 




(Earth's as 1000). 




(Earth's as 100). 


The Sun . 


315,000,000 


< 


i 


— 


Mercury . 


65 


• 


, 


39 


Venus . 


885 


v , 


, . 


72 


The Earth and Moon . 


1,012 


• , 


• 


100 


Mars 


118 


, , 


• 


152 


(Hero intervenes tlio family 










of tho Asteroids.) 










Jupiter . . 


300,860 


• < 


• 


520 


Saturn . . , 


89,692 


• 


» . 


954 


Uranus . 


12,650 


• 


» . 


1,920 


Ncptuno . 


16,773 


• 


. 


3,004 



The mass of all the asteroids together amounts 
probably to 100 on the above scale, or about one-tenth 
part of the earth (Leverrier has shown that the asteroids 



How the Planets Grew. 185 

cannot be equal to a fourth of the earth in mass); and 
we may set their mean distance of about 275 on the above 
scale. 

Now, here we see that the system is divided into two 
families perfectly distinct from each other, and each 
consisting of four primary bodies. If we add up the 
masses of each family, we get for the inner family 2,068, 
and for the outer family 419,975— -that is, the outer 
family exceeds the inner in mass more than 200 
times. The sun, however, exceeds even the outer family 
about 750 times in mass; and the inner family exceeds 
the intermediate family of asteroids about twenty times, 
probably, and certainly more than eight times in mass. 

Here is already a wide diversity of distribution. And 
taking the families in order from the sun — the great 
ruling mass — we find nearest to him neither the most 
massive nor the least massive family, but the family of 
medium mass. The family of least mass has the medium 
position in the system, and the family of greatest mass is 
outside. 

Again, while the most massive family travels outside 
the two other families, the two most massive members of 
that family travel within the two of inferior mass. Yet 
of these two the outermost is the larger. 

A like diversity of structure is found in the innermost 
family, to which our earth belongs. The least primary 
member of the family travels nearest to the sun, the 
second is much larger, and the third larger still. But 



1 86 The Expanse of Heaven. 

there the progression stops, the third being the largest of 
all, and the fourth the smallest but one of the primary 
members of the inner family. 

I do not know of any means of accounting for all 
these peculiarities of arrangement. It would perhaps be 
as difficult to account for all the peculiarities of shape 
and development in a tree. But as the general features 
of a tree are accounted for by what we "know of the 
laws of tree growth, so I conceive that any true theory of 
the growth and evolution of the planetary system should 
be competent to account for the general features of that 
system. It appears to me that Laplace's theory of the 
evolution of # the system through the gradual contraction- 
of a vast rotating disc of vapour accounts for none of these 
general features, but, on the contrary, the processes he 
conceived would lead to a general uniformity of structure 
such as the planetary system does not possess. I do not 
mean that all the planets would be equal in mass if the 
system had been formed as Laplace supposed, but that 
they should be arranged in order of mass according to 
some recognisable law connected with their arrangement 
in order of distance. 

In searching for another theory of the evolution of our 
system we may take into account the point to which I re- 
ferred in my last chapter — viz. that Laplace's theory does 
not correspond with processes taking place at the present 
time. We may enquire whether any process of develop- 
ment is now taking place, actively or otherwise. And 



How the Planets Grew 187 

then, if we can recognise any such process, I think it will 
be worth while to consider whether this process in some 
former more active season of its action might not be found 
to give a better account of the evolution of the planetary 
system than that impossible process of nebulous rotation 
which Laplace conceived before it was as yet known that 
the process is impossible. 

It seems to me that this is the proper way to search 
for an explanation of the growth of our system. If we 
were ephemera and were desirous of determining how a 
tree had arrived at its present condition, we might, if 
we pleased, imagine that some great mass of vegetable 
matter had shrunk into tree shape, or we might equally 
well at the beginning of our labours imagine that the 
tree had grown from some prior inferior form until it had 
assumed its present dimensions. But if, as ephemeral 
life proceeded, generation after generation gathering 
knowledge, we ascertained that the tree was still growing 
(though very slowly) by such and such processes, I con^ 
ceive that the natural result would be to prefer the theory 
of growth to the theory of contraction. If further 
enquiry showed the theory of contraction to be inadmis- 
sible, because it was found that no vegetable masses, such 
as those which had been conceived to produce trees by 
a process of contraction, either did or could exist, we 
should find ourselves still further attracted to the theory 
that the tree had grown. And if, on careful examination 
of the evidence, it was found that the general features of 



1 8 8 The Expanse of Heaven. 

the tree could be explained by supposing that the present 
process of growth had once taken place much more 
actively, then I think a reasonable May-fly could form but 
one opinion. 

He might not indeed conclude certainly that the tree 
had grown by those particular processes ; but I think he 
would not be a rash ephemeron if he regarded that view 
of matters as altogether more probable than any theory 
of contraction. Nor, I think, would he deserve to be 
blamed by other ephemera (not given perhaps to original 
investigation, and greatly submissive to the authority of 
eminent names) who would point out that the contraction 
theory had been advocated in former ephemeral periods by 
a highly distinguished ephemeron, whose opinion was not 
to be lightly opposed. I conceive that our modern and 
innovating May-fly might reasonably reply to such censure, 
that while the memory of the eminent ephemeron of 
former hours was certainly to be held in all respect, yet 
his views could properly be opposed, for the simple reason 
that much new knowledge had been gained respecting 
the universe — that is, the tree — in the hours — nay, even 
whole days — which had passed since his hour. 1 

Viewing our universe in the same way, I think we can 

1 A student of astronomy, not wholly unknown to me, has used some 
such arguments in defending himself from the charge of audacity in main- 
taining new views respecting the stars against the authority of the deservedly 
eminent astronomer Sir W. Herschel, and in controverting the arguments 
of the great mathematician Laplace respecting the evolution of our solar 
system. I think his reasoning is fair enough. 



How the Planets Grew. 189 

more hopefully discuss past processes resembling in nature, 
though not in degree, those at present taking place than 
the contraction of impossible nebulous masses. 

Now, so soon as we turn our thoughts to meteoric 
indraughts as the source whence planets gathered their 
substance, we begin to see reasons for the general features 
of the solar system. 

In the first place, we should expect planets near the 
sun to be small. For the sun's enormous might, exerted 
from the beginning of his existence as a central aggrega- 
tion, would cause all meteors which passed within moderate 
distances from the sun (within such distances, let us say, 
as two hundred millions of miles) to have at those dis- 
tances enormous velocities. We know what such velocities 
would be, supposing such meteoric masses to have 
travelled sunwards from very great distances. Quite close 
to the sun the velocity would be about 380 miles per 
second, and 200 millions of miles from him it would be 
about eighteen miles per second. It would be meteors 
rushing along with velocities ranging between these which 
would have to be captured to make planets within mode- 
rate distances of the sun. Velocities so great would give 
them power to escape for the most part. Only those 
actually impinging on the gathering minor aggregations 
would be captured. 

It would be at some great distance — say, such a dis- 
tance as Jupiter's — that the first really important secondary 
aggregation (the sun being regarded as the great primary 



1 90 The Expanse of Heaven. 

aggregation) would be formed. Here there would be still 
abundance of material, but the great reduction of velocity 
at this distance (whether matter arriving at its journey 
sunwards were considered or matter voyaging away after 
close passage round the sun) would give a gathering mass 
the power to capture more matter, and so by growing 
rapidly to acquire fresh influence, and soon to become 
pre-eminent among all the subordinate aggregations. 

Here, then, we should have the giant planet of the 
universe — not so far from the sun that the matter travel- 
ling hither and thither would be too greatly reduced, but 
so far away that such matter would not move too rapidly 
to be readily captured. 

Outside this great secondary aggregation there would 
be aggregations smaller and smaller, owing to a reduction 
in the quantity of matter not compensated by the now 
slow reduction of the velocities. For while in the sun's 
neighbourhood a distance of 200 millions of miles re- 
duces the velocity from 380 miles per second to eighteen 
miles per second, the velocity at Jupiter's distance is 
eleven miles per second, at Saturn's eight, at Uranus' 
six, and at Neptune's nearly five miles per second, a very 
much smaller proportionate reduction. 

And I think that the general features of the system 
within the orbit of Jupiter are fairly accounted for by the 
theory of meteoric aggregation. For close to the sun the 
great velocities would enormously overbalance the great 
excess of material here. We should see then the least 



How the Planets Grew. 191 

member of the inner family nearest to the sun. There 
would be a gradual increase of size and importance until 
a maximum was attained in the case of the earth, and then 
as gradual a falling off towards the zone of asteroids — the 
region, on this view, where the influence of Jupiter on 
the one hand and the sun on the other would each operate 
to prevent the formation of a subordinate aggregation, 
though not preventing a cloud or flight of relatively in- 
significant aggregations from forming. 

I do not pnter further here into the details of this 
theory, because I have already considered them fully in 
my ' Other Worlds.' I must, however, note one point. It 
may seem at a first view that this theory of the evolution 
of the solar system is inconsistent with the views I have 
enunciated as to the formation of the larger comets by 
eruption from suns, and of minor comets by eruption 
from the major planets. But it is not to be supposed 
that in the earlier stages of the history of our system 
matters were as they are now, and even now it may well 
be believed that enormous quantities of as yet ungathered 
materials are moving hither and thither throughout space. 
Growth and decay go on pari passu. 

To revert to the tree which has already afforded so 
many illustrations of evolution theories — and illustrations 
so just in my opinion — we see that trees are continually 
throwing out matter, in leaves, buds, bloom, and fruit, 
which, falling eventually from the tree, is in a sense lost 
from its substance. This may be compared to the erup- 



1 9 2 The Expanse of Heaven. 

tion or other emission of matter from the sun, and pro- 
bably from the major planets of the system, as well in the 
present time as in long past ages. But this does not 
prevent us (and should not prevent a reasoning race of 
ephemera) from believing that the tree has grown con- 
tinually even while such processes of throwing-off or loss 
have continued. Indeed, so constantly do we find the con- 
tinuous gain of bulk which we call growth accompanied 
by as continuous a loss of matter, that it would be almost 
a fatal objection to any theory of the evolution of our 
system if it should fail in presenting this analogy to other 
known forms of growth. 

But, intleed, it would be a mistake to suppose that we 
have gone back to the beginning of our system's history 
in showing how its present condition was probably evolved 
from a former condition. To quote words which I used 
two years ago in my book on the sun, ' In thus looking 
back at the past history of our system, we have passed after 
all but a step towards that primal state whence the conflict 
of meteoric matter arose. We are looking as into a vast 
abysm, and as we look we fancy we recognise strange 
movements, and signs as if the depths were shaping 
themselves into definite forms. But in truth these move- 
ments show only the vastness of the abysm, these depths 
speak to us of far mightier depths within which they are 
taking shape. ' Lo ! these are but a portion of His ways ; 
they utter but a whisper of His glory ! ' 



OUR DAILY LIGHT. 

God said, Let there be light, and there was light. — Genesis i. 3. 

We are in the habit of regarding the sun as a constant 
source of light and heat, to which we may always trust, 
day after day, year after year, and century after century. 
And yet if we follow the only evidence which we have 
upon the subject —apart, of course, from that continual 
supply of light and heat which the sun has afforded during 
past ages — we might well be disposed to feel doubt on the 
subject. When we consider the stars, and remember that 
they are suns like our own, we may look to them for in- 
formation as to the general laws according to which the 
suns which people space exist — our own included. If we 
find among the stars the signs of change, some stars 
growing fainter, others growing brighter, some fading 
altogether from view, and others which had been invi- 
sible becoming conspicuous objects, we should be led to 
doubt whether the light of our sun may not one day wane 
or wax in lustre, whether he may not lose so much of his 
brightness as no longer to supply the wants of the 
creatures living upon the different planets of his system, 



1 94. The Expanse of Heaven. 

or, on the other hand, blaze forth with so surpassing a 
splendour as to destroy those creatures by his excessive 
glory. 

Now, although the stars do not teach us in this way to 
regard the sun's light and heat as Vtkdy to change very 
remarkably in the course of a moderate interval of time, 
yet changes sufficiently remarkable take place among them 
to show that we cannot place absolute reliance on the per- 
manence of our sun's light and heat. I propose to con- 
sider a few instances of such changes. 

Everyone knows the group of stars called Charles's 
Wain, consisting of seven conspicuous stars, three of 
which have been compared to the horses, while the remain- 
ing four indicate the outline of the wain or waggon. We 
have it on the authority of the most ancient records re- 
specting the stars that these seven stars were once nearly 
equal in brightness. And in star lists made rather more 
than two hundred years ago we find that each of the 
seven was recorded as a star of the second magnitude. 

We know further that Bayer, who assigning the Greek 
letters to the stars of a constellation followed as nearly 
as he could judge the order of brightness, gave to the 
middle star of the seven the fourth letter of the Greek 
alphabet, Delta. Now anyone who looks at that star 
group can see at once that this middle star of the set of 
seven is very inferior to the others in brightness. It is, 
in fact, now ranked as a star of the fourth magnitude, 
which implies, according to the best modern measurements 



Our Daily L ight. 195 

of stellar brightness, that it gives out now about one-third 
part of the light that it gave out in former years. It is 
not known when the change took place ; but it is certain 
that the star has thus sunk in brightness within the last 
two hundred years. 

Now, this star is probably a larger orb than our own 
sun. There are reasons for believing that the five middle 
stars of the seven — that is to say, all but the farthest 
horse on one side, and the opposite angle of the wain on 
the other — are orbs forming a single family ; and from a 
certain peculiarity which these stars exhibit in common, 
when examined by the spectroscope, it is inferred that 
they belong to a class of suns far larger than our own. 
But, whether this be so or not, it is certain that the four 
bright stars of the five are not inferior to our sun in the 
quantity of light they give out. The same was formerly 
true, of course, of the star which has lost, as we have seen, 
so large a proportion of its brightness. 

Now let us try to picture what is meant by the change. 
Let us try to conceive what would have been the fate 
of creatures inhabiting our earth if the sun's light and 
heat had decreased in the same degree during the same 
short interval of time. Two hundred years may seem, 
indeed, a long period when compared with the duration of 
a single human life ; but compared with even the history 
of a nation, it is little ; while it sinks into insignificance 
by comparison with the intervals of time which history has 
to deal with. 



1 96 The Expanse of Heaven. 

Imagine what must have happened if, since the reign 
of Queen Elizabeth, our sun had lost his light and heat 
until he gave out less than a third of his usual supply. 
The loss of light and heat, so far as it affects merely the 
comfort of creatures living on the earth, would be of 
small importance. We bear without inconvenience the 
darkness of a cloudy day, or of many cloudy days in suc- 
cession. We can endure protracted seasons of cold, so 
that, though we should be doubtless rendered uncomfort- 
able by the change, it would not be absolutely unbearable 
so far as its direct effects would be concerned. But we 
must remember how wonderfully the various forms of life 
on our earth are adapted to the conditions which surround 
them. This is true of animal life, though some animals 
can bear change of climate and of place better than 
others : but it is especially noteworthy in the case of 
vegetable life. Every region of the earth has its own 
forms of plant life, unsuited to other regions, and in- 
capable not merely of thriving but even of living anywhere 
save in their own habitat, or at least in some region very 
closely resembling their native place in all the chief cir- 
cumstances which affect plant life. Now, a loss of even 
a third part of the sun's light and heat would correspond 
to a change in the conditions of the various forms of 
vegetable life which could not possibly be survived except 
by a few of the hardier sort. But if the sun, like the 
star Delta of the Great Bear, lost two-thirds of his lustre, 
it is certain that in a very short time scarcely any form of 



Our Daily Light. 197 

vegetable life would remain upon the earth. And it need 
hardly be said that animal life would inevitably perish if 
vegetation were destroyed from the face of our globe. 

But the changes which have taken place in some stars 
have been far more remarkable. * 

In the constellation of the ship Argo there is a star 
which was recorded in Lacaille's Catalogues (in 1751) 
as of the second magnitude. Now, in 1677 our English 
astronomer Halley had described this star as of the 
fourth magnitude only ; so that in the interval of eighty- 
four years (or less) this star had increased as greatly in 
brightness as the star Delta in the Bear has diminished. 
In 1811 and 1815 this star had again sunk to the fourth 
magnitude. But no long period elapsed before it had 
resumed its position as a star of the second magnitude. 
This was in 1826, and here it might be supposed were 
changes sufficiently remarkable. But a year later this 
star had risen to the first magnitude. Then, after re- 
turning for a while to the second magnitude, it increased 
again in brilliancy, until in 1838 it was one of the 
brightest of the first magnitude stars. It then diminished 
slightly, still, however, remaining in the first rank, until 
1843, when it increased again until it very nearly equalled 
Sirius itself in brightness. From that time it diminished 
rapidly, until in 1863 it could only just be seen on the 
darkest and clearest night. It has remained thus faint 
during the last ten years. 

Changes such as these — or even one of these changes 



198 The Expanse of Heaven. 

— if occurring in the case of our own sun, would destroy 
life very quickly from the face of the earth, and probably 
from all the inhabited planets of the solar system. The 
mere change from the second magnitude to a brightness 
approaching that of Sirius implies an increase of emission 
of light and heat more than tenfold. But from this 
amazing access of splendour how wonderful has been the 
falling off by which the star has been rendered almost 
invisible. It is absolutely certain that this star, once 
doubtless a sun, and probably like our own sun the centre 
of a scheme of circling worlds, gives out, day by day, 
far less than the hundredth part of the light and heat 
which it gave out daily only thirty years ago. 

There are also cases where stars which had long been 
known to astronomers have disappeared altogether from 
view, so that their place knows them no more. It is 
possible that they may still give out some degree of 
]ight and heat, but the most powerful telescope fails to 
afford any sign of their existence, so that so far as our 
astronomers are concerned these stars must be regarded 
as extinguished suns. It is at least certain that they 
have lost so large a proportion of the light and heat they 
once possessed, that the change must seriously have 
affected the condition of beings living in the planets 
which doubtless circle around these once brilliant orbs. 

But the sudden appearance of a new star is even more 
suggestive of the possibility of future change. Astro- 
nomers now know that those stars which have appeared 



Our Daily Light. 199 

for a short time, shining with great brilliancy, insomuch 
that they have sometimes surpassed even the leading 
stars of the heavens in brightness, are not in reality 
new stars. They are known stars, which after shining 
for a long time with but a faint lustre, have suddenly 
blazed out, owing to some mighty catastrophe which has 
taken place. 

An instance of the kind occurred seven years ago, 
when a star suddenly appeared in the constellation of the 
Northern Crown, shining as a star of the second magnitude. 
It was found that it occupied the same place as a star of 
the tenth magnitude, and no doubt now exists that it was 
this known faint star which had thus suddenly acquired a 
new brilliancy ; for though the star soon lost its great 
brightness, it can still be seen, as before, as a star of about 
the tenth magnitude. Now, when the star (appropriately 
called the Blaze Star) came to be examined with the 
spectroscope, it was found that a great portion of its light 
came from glowing hydrogen. Doubtless, by some 
circumstances the exact nature of which we shall never 
know, there had been a tremendous conflagration in that 
distant star. It was estimated that the brightness of the 
star increased fully eight hundred fold while this confla- 
gration was in progress. 

If a change such as this took place in our own time — 
and who shall say that such a change is impossible ? — the 
prophecy of St. Peter would be fulfilled : < The day of the 
Lord will come as a thief in the night ; in the which the 



200 The Expanse of Heaven. 

heavens shall pass away with a great noise; and the 
elements shall melt with fervent heat : the earth also, and 
the works that are therein shall be burned up.' For 
aught that is certainly known, the mere daily continuance 
of the sun's light and heat may be due to causes which 
need only be excited to unusual activity to produce such a 
catastrophe. We know now that the sun is undergoing 
processes which, although regular in their effects regarded 
as a whole, are locally irregular. Sometimes there are 
outbursts in the sun, which suggest very significantly the 
possibility of much more terrible, because more general 
catastrophes. 

It seems, for instance, that a great local increase of 
solar action is produced when large meteoric masses fall 
upon the sun. Now, if it chanced that some large comet, 
arriving from outer space, should fall directly upon the 
sun, it is most probable that (as Newton once suggested) 
the effect would be a great, though temporary, increase in 
the sun's light and heat. Some comets have come near 
enough to remind us of the possibility of such a catastrophe. 
Newton's Comet (1680) passed at a distance of less than 
a third of the sun's diameter from his surface, and the 
comet of 1843 came even nearer. A very slight change 
in the direction of either comet, when still at a great 
distance from the sun, would have led to the catastrophe 
Newton feared. It may be that the catastrophe would do 
little harm, or would only affect the comet itself. But 
for my own part I cannot but think that the inhabitants 



Our Daily L ighL 201 

of this earth have far more to fear from the fall of a comet 
^ipon the sun than from the once dreaded collision of a 
comet with our earth. It is no unreasonable inference 
that the great conflagration which caused the star in the 
Northern Crown to blaze out so remarkably, was produced 
by the downfall of a comet or flight of meteoric masses 
upon that orb. In this case it is quite within the bounds 
of possibility that our sun may one day experience a similar 
fate. 

We are apt to forget these possibilities, ' for since the 
fathers fell asleep all things continue as they were from 
the beginning of the creation. For this we willingly are 
ignorant of, that by the word of God the heavens were of 
old, and the earth standing out of the water and in the 
water ; whereby the world that then was, being overflowed 
with water, perished ; but the heavens and the earth which 
are now, by the same Word, are kept in store, reserved 
unto fire against the day of judgment and perdition of 
ungodly men. But one day is with the Lord as a 
thousand years, and a thousand years as one day. . . . 
Seeing then that all these things shall be dissolved, what 
manner of persons ought we to be in all holy conversation 
— looking for the coming of the day of Grod, wherein the 
heavens, being on fire, shall be dissolved, and the elements 
shall melt with fervent heat, 5 



202 The Expanse of Heaven. 



THE FLIGHT OF LIGHT. 

Be not ignorant of this one thing, that one day is with the Lord as a 
thousand years, and a thousand years as one day. — 2 Peter iii. 8, 

One of the most startling thoughts suggested by the 
study of the heavens on a dark and clear night, is the 
recollection that what we look at is not what is actually 
in existence as seen. We turn our eyes to the blazing 
Sirius, and it seems incredible that in reality we are not 
looking at that noble Sim as it is now, but as it was 
fifteen or twenty years ago. Yet nothing is more certain. 
The rate with which light travels has been measured in 
several ways, and no question can remain as to the 
accuracy of the result. It is certain light does not travel 
at a greater rate than 190,000 miles per second. Again, 
it is certain that Sirius lies at least a million times 
farther away from us than our sun. 

Now, light takes more than eight minutes in reaching 
us from the sun, whose distance is more than 91,000,000 
of miles ; and it is easily calculated that the long journey 
from Sirius cannot be traversed in less than fifteen years. 
More probably it requires upwards of twenty years ; and 
the greater number of the stars we see on a dark and 



The Flight of Light. 203 

clear night lie very much farther away than Sirius. 
Some of them certainly lie at distances which light can 
only traverse in hundreds of years. So soon as we turn, 
however, to telescopic stars, the range of time over which 
our vision extends is enormously increased, and it is 
certainly not too much to say that some of the fainter 
stars revealed by the great Eosse telescope lie at distances 
so enormous that their light has taken more than a 
hundred thousand years in reaching us. Then beyond 
these stars lie millions and millions of orbs yet farther 
away. There is no limit to the range of space occupied 
thus with the work of God's hands. All that has been 
taught us by astronomy suggests the lesson that every 
moment light reaches this earth from unseen orbs so far 
away that the journey over the vast abysses separating us 
from them has not been completed in less than millions 
of years. 

And here a wonderful thought presents itself. We 
see the starlit heavens with the small organ called the eye, 
opening by a circle less than a quarter of an inch in 
diameter upon all these wonders. The telescope has 
enhanced the power of this organ, but the telescope does 
not, like the unaided eye, show the whole of the starlit 
sky at once. Yet again, even the telescope is but a 
minute instrument when compared with the very least 
of the celestial objects which it reveals. Now, if it be 
remembered that our estimates of the wonders of creation 
have been formed by these imperfect, these utterly feeble 



204 The Expanse of Heaven. 

means, we begin to perceive that our conceptions of the 
universe are as nothing compared with the reality. 

Imagine for a moment what would be seen if each one 
of us possessed a power of vision exceeding a million-fold 
that given by means of the Eosse telescopes. This 
conception, startling as it seems, does not alter the reality. 
The wonders we should then see exist, though they are 
unseen. They may be manifest to beings unlike ourselves, 
to the angels and ministers of the Creator. But whatever 
opinions we form on this point, we must not doubt that 
to the Creater Himself they are more than manifest. All 
our senses cannot suggest to us the absolute knowledge 
which He possesses of all His universe. We see, and 
touch, and smell, and taste, and hear, and thus come to 
know some little about the things nearest to us. But 
our knowledge even of such things is imperfect. And 
these senses are but five among myriads of possible senses, 
each one of which would add some new knowledge about 
every existent object. 

The range of our senses, also, is exceedingly limited. 
We can understand this even from what we know of 
other creatures. The sense of smell in the dog, for 
example, is a sense utterly unlike our human sense in 
the information it conveys to the animal possessing it. 
A dog lives and moves among smells even as a man lives 
and moves among sights ; it is probable even that some 
dogs can recognise the shape and something of the 
constitution of objects by the sense of smell, as perfectly 



The Flight of L ight. 205 

as man by the sense of sight, and in some cases even more 
perfectly. The insect, again, possesses a range of vision 
and of hearing, possibly also of feeling, and smell, and 
taste, altogether unlike the corresponding range in the 
case of our senses. There are noises too shrill to be heard 
by our ears, which are clear to the audition of the insect. 
There are colours which to our eyes are as darkness, while 
to the insect they are beautiful, though with a beauty we 
are unable to conceive, since so feeble are our mental 
senses that we cannot even picture to ourselves colours, 
or imagine sounds, which our experience has not rendered 
familiar to us. And on the other side of the range of 
the senses, it is probable that the elephant, rhinoceros, 
hippopotamus, and bison, possibly also the whale and 
other large creatures, can recognise sounds too deep for 
human ears, 1 and perhaps colours beyond that red end of 
the spectrum where human vision ceases to distinguish 
colour. It may be added that even among men the 
range and the power of the senses vary considerably, thus 
reminding us of the fact that the senses are limited in 
their action, and indicating the possible existence of 
senses of the same kind, but of far greater range and 
power. 

But so soon as we have taken these considerations 
fairly into account we begin to see that the aspect 

1 The deep mooing of the ox is probably the medium note of that 
animal's sound scale, and a similar conclusion may reasonably be formed 
in the case of other animals whose ordinary tones are exceptionally deep. 



206 The Expanse of Heaven. 

presented to us by the universe, either as actually seen or 
as revealed by the telescope, depends solely upon the 
powers and attributes given to man by his Creator. 
What we know of the universe is what our senses enable 
us to know, and is very far indeed from affording a true 
measure of the real universe, either in extent or in the 
complexity of its structure, or in the splendour of its 
various parts. In particular, and it is to this point that 
the considerations I have been dealing with have been 
directed, our senses are such that only one of them, sight, 
gives any evidence at all of the greater part of the 
universe, while this sense is so related to the peculiar 
form of motion we call light, that it can only tell us 
about any single part of the universe, as that part was at 
a particular instant^ so many years ago. It cannot bring 
into one picture the universe (or that portion of it which 
it reveals to us) as it all existed at any given time. 

We learn by a view of the heavens that twenty years 
ago Sirius was shining with such and such brightness; 
that a hundred years ago some other star was shining 
with its degree of lustre, and so on ; but the star depths 
are never revealed to us exactly as they are at the 
moment, or exactly as they were at any moment. Yet 
this is merely due to the imperfection of our senses. We 
judge by the light of these objects, and this light travels 
at such and such a rate. It is conceivable that creatures 
might have a sense enabling them to judge by some 
other form of action, exerted by the stars, as for instance 



The Flight of Light. 207 

by the action of gravity. If gravity were the action thus 
effective, the information conveyed respecting the universe 
would be far more nearly contemporaneous, since the 
action of gravity certainly travels many thousands of 
times faster than light, 1 even if it do not travel with 
infinite velocity as some philosophers suppose. 

Thus we see that even only imagining the Creator to 
possess senses such as we have, but much more powerful, 
the aspect of the universe to Him would be very different 
from that which is presented to ourselves ; and still more 
would this be the case if we conceived Him to possess 
senses by which other forms of force than our senses deal 
with would convey their information respecting the 
universe. Not only would a contemporaneous picture be 
presented through the action of some of these senses, but 
other senses would convey information such as our ordinary 
senses do not convey. 

For the present, however, let us confine our attention 
to the teachings of the sense of sight, and reflect on some 
of the lessons which are suggested by the thought of what 
would follow from a great increase in the power and 
range of this sense. Let us dwell, in particular, on the 
startling thought that this sense, so enhanced, would 

1 This is not a matter of conjecture. It has been shown that if gravity 
travelled with a velocity equal only to that of light, the motions of the 
planets would be utterly different from those which have been observed 
since astronomy was a science ; and a difference readily detectable would 
have resulted, even though gravity travelled a thousand times or a million 
times faster than light. 



2o8 The Expanse of Heaven. 

reveal to the creatures possessing it the history of long 
past events. 1 I use the word ' history ' because, as a 
matter of fact, sight, like the other senses, conveys 
information about an event, and does not, as we are in 
the habit of supposing, reveal the event itself. The 
information is in all ordinary cases so direct and immediate, 
that it seems to us as though the event itself had been 
disclosed. But what has really happened has been that 
certain light-waves have communicated certain impres- 
sions to the optical nerve, and thence to the brain, and 
so the lesson has been conveyed that such and such events 
had transpired. 

To return, then, to the creatures supposed to possess 
enhanced powers of sight : — They would be informed of 
the past. We are thus informed of the past history of 
the stars we see. But imagine only that we could see 
those stars (from our distant stand-point) so clearly that 
not only the shape and dimensions of their globes, and 
the nature of the processes taking place around and upon 
them were revealed, but that the worlds circling around 
them, and all that is — no, that ivas — taking place upon 
them, could be seen! Then we should be looking on 
while events which really happened many years ago were 
represented before our eyes. In ordinary speaking, we 



1 It is, perhaps, hardly necessary for me to remark that many of the 
considerations which follow have already been dealt with by the anonymous 
author of the ingenious and interesting little work called * The Earth and 
the Stars/ 



The Flight of Light. 209 

should see these events taking place, and yet in reality 
not only would these events have happened (in the case 
of most stars) long ago, but probably the creatures taking- 
part in them would long since have passed out of exis- 
tence. 

It is when we imagine a converse process applied to our 
earth that the thoughts suggested become most instruc- 
tive. Events have happened on our earth and have been 
forgotten, which, nevertheless, are at this very instant of 
my writing visible from some one or other of the orbs 
which people space, if only there are creatures on those 
orbs possessing such enhanced powers of vision as I have 
spoken of ; and there is no event of such a nature as to 
be visible from standpoints without the earth, which has 
not been thus rendered visible over and over again as the 
light-messages conveying its history have passed beyond 
star after star (in all directions from the side of the earth 
on which such events took place) ; no such event which 
will not be thus rendered visible over and over again 
hereafter as the light-messages travel onwards into the 
star depths for years, for centuries, for millions on millions 
of ages, until time shall be no more. 

Now, the conception of such powers of vision in 
creatures made by God's hands may be regarded as fanci- 
ful, though I apprehend that our ideas in such matters 
are very imperfect and feeble, and afford no measure of 
what is possible. But that the Almighty Himself is 
cognisant of all these light-messages who can question ? 



2 1 o The Expanse of Heaven. 

To Him who is everywhere, the light-record of all that 
has taken place on earth is being continually conveyed, 
the remembrance is ever present with Him ; ' the eyes of 
the Lord are in every place beholding the evil and the 
good,' 'His eyes are upon the ways of man, and He seeth 
all his goings.' 

But, lastly, let us remember that even these thoughts, 
startlingly though they impress upon us the fact that 
nothing that is done shall be forgotten, are altogether 
imperfect. It is well for us to form some idea of the 
all-seeing vision of God, by speaking of the eyes of God, 
and by comparing His knowledge with that direct know- 
ledge of events which we obtain by means of the sense of 
sight ; but we must not forget that this mode of speaking 
is really as far from the truth as are the poetical expres- 
sions by which the inspired writers speak of the might of 
God's arm, or of His holding man as in the hollow of His 
hand. There is that continual record of events by means 
of light-waves travelling for ever and ever through space ; 
and beyond question, the Almighty is as cognisant of 
those light-waves as of any event actually taking place 
in this world or in others. But His knowledge is infi- 
nitely more perfect and complete than any we obtain 
even of the simplest events by means of our senses. 
6 God looketh to the ends of the earth, and seeth under 
the whole heaven. No thought can be withholden from 
Him.' 



A CLUSTER OF SUNS. 

There shall be no night there. — Rev. xxi. 25. 

In the previous chapter I spoke of the existence of senses 
— that is, means of judging of external things — unlike any 
that are possessed by mankind. It appears to me that 
the study of astronomy is calculated to suggest ideas of 
the kind, thoughts of what is unfamiliar to us, conceptions 
of states of existence even unlike any that we know of. 
For in studying astronomy we find ourselves brought into 
the actual presence of systems where much must neces- 
sarily be quite different from what we experience here on 
earth. It is of a system of this kind that I propose now 
to speak. 

When we search the heavens with powerful telescopes, 
we perceive besides the stars certain cloudlike objects, 
which have been called nebulce, from a Latin word sig- 
nifying a cloudlet. There are many hundreds of these 
objects of various orders. But my present purpose is to 
consider only one class of celestial cloudlets — the star 
clusters. For many of these cloud-like objects, when 
examined with suitable telescopic power, are found to 

insist of myriads of stars. Within a minute space of 
10 



2 1 2 The Expanse of Heaven. 

the heavens, since even in the telescope many of these 
cloudlets remain exceedingly small, thousands on thousands 
of suns are seen, and probably many thousands of suns are 
there also which are unseen, because smaller than the rest. 
Some of these objects are amazingly beautiful and splendid, 
insomuch that it has been said of one of them — a cluster 
called 1 3 Messier in Hercules — that probably no one who 
has beheld this cluster for the first time in a telescope 
of great power has been able to refrain from a shout of 
wonder. 

Now, it was formerly held that these clusters of stars 
are in reality galaxies like our own Milky Way, sidereal 
systems whose stars are suns like our own separated from 
each other by distances like those which separate our sun 
from his neighbours among the stars. But certain very 
simple considerations oppose themselves to this view of the 
nature of the star- clusters, and show that they are really 
distinct in their nature from that part, at any rate, of the 
sidereal system to which our sun belongs. When we see 
one of these clusters of a rounded figure as a whole, and 
also gathering more and more richly towards its centre, 
always with a uniform roundness for each order of rich- 
ness, we are certain that we have in view a globular system 
of suns. And when we look at any globe-shaped object 
of any apparent size, we know within what limits of relative 
distance the different parts of that object lie. 

To explain my meaning — if there is a soap-bubble an 
inch in diameter, and a yard from the eye, we know that 



A Chester of Sims. 2 1 3 

the farthest point of that bubble is farther than the nearest 
point by a thirty-sixth part of the bubble's distance ; so 
much we could learn, let us say, by measurement : but if 
that bubble, so placed, looked just as large as a balloon 
very much farther away, then, although we could not tell 
by measurement how far off the balloon was, we should 
know without measurement that precisely the same re- 
lation held in the case of the balloon — namely, that its 
farthest point was farther away than its nearest point by 
a thirty-sixth part of the balloon's distance. And if the 
soap-bubble just concealed a star-cluster, or the sun, or 
moon, or in fact any globe-shaped object at any distance 
whatever, precisely the same relation would hold. Ac- 
cordingly, though astronomers have no means of measuring 
the actual distance of any star-cluster — or, at any rate, 
have not yet succeeded in effecting such measurement — they 
can infer with great certainty within what limits of relative 
distance the parts of such clusters lie, because they can 
very accurately measure the apparent size of any star- 
cluster. Only, before passing from the soap-bubble illus- 
tration, let me warn the reader not to imagine that any 
star-cluster is so large as that illustration might suggest — 
a pin's head, at a yard's distance, would look larger than 
most of the chief star-clusters. 

Now, when such a process has been applied, it is 
found that the farthest star in a star-cluster of the 
brighter and richer order cannot be at a relatively much 
greater distance than the nearest star of such a cluster ; 



214 Th Expanse of Heaven. 

and when due account is taken of the enormous number 
of stars in such clusters, it follows that, on a very moderate 
computation, the distance separating star from star in 
the heart of a rich cluster must be less than a mil- 
lionth part of the distance separating the cluster from 
our sun. 

But we can see the separate stars of these clusters, 
and sometimes with telescopes of no great power. We 
may, then, regard the stars thus seen as of at least the 
twentieth order of magnitude — that is, shining as brightly 
as stars of the first magnitude removed to but twenty 
times their present distance. 1 If, therefore, we could 
approach one of these clusters until we were within one- 
twentieth of its present distance, we should see its lead- 
ing stars shining as stars of the first magnitude. But we 
should still be fifty thousand times farther from the 
cluster than its component stars are from each other, 
at least in the rich central region of such a cluster. 
What, then, would happen if we could continue our 
imagined journey until we were in the very heart of the 
cluster of suns ? 

It is very easy to answer. Suppose we were then 
midway between two leading suns of the group, then 
we should be at a distance from either equal to only 
the one hundred thousandth part of that which had 

1 Tlieso statements aro all far within the truth, and are presented in 
their present form to avoid the necessity of a detailed account of the esti- 
mates of astronomers respecting star magnitudes. 



A Cluster of Stcns. 2 1 5 

separated us from the cluster when its leading brilliants 
shone as first magnitude stars. These two suns then 
would shine, not a hundred thousand times, but a hundred 
thousand times a hundred thousand times more brightly 
than our first magnitude stars. That is, they would 
shine ten thousand millions of times more brightly than 
Arcturus and Betelgeux, Capella, Vega, and Aldebaran. 
But this is equivalent to saying that they would each 
shine as a sun not quite so brilliant as our own sun, but 
still with much more than sufficient brightness to give 
broad daylight to any world placed where we have sup- 
posed our voyager to have arrived. 

This, however, is far from being all. I have spoken 
thus far of but two stars out of the thousands on thousands 
composing the star-cluster. All these thousands would 
shine with a brightness enormously exceeding that of any 
of the stars we see, and many hundreds among them 
would appear as suns, smaller than the two nearest suns 
before considered, but bright enough with their sole 
lustre to banish night. 

It follows, then, that to a globe placed as we have 
supposed, and travelling around one or other of the suns 
composing the cluster, night would be absolutely un- 
known. There would be different degrees of daylight, 
from the broadest day on the part of the globe turned 
fully towards the nearest sun, to a less brilliant day on 
the opposite part turned to other suns, but always day, 
often very much brighter than our summer noon, and 



2 1 6 The Expanse of Heaven. 

seldom fainter, since the number of suns would make up 
for the comparative smallness of each. 

Here, then, is a state of things utterly unlike any 
with which we are familiar. We can hardly suppose that 
those distant star-clusters are mere barren lights, when 
we remember that they are among the most stupendous 
creations in the universe. We know that the component 
stars are suns such as ours ; we know that these suns are 
counted by thousands and tens of thousands : we cannot 
imagine that all this wealth of matter is glowing without 
any purpose. We conclude, then, that there are worlds 
within that cluster, and the condition of such worlds can 
be no other than that which has been described above. 
There is perpetual light, a perpetual supply of heat ; there 
are no seasons, no days, and, so far as we can judge, it 
can be a matter of no moment to the inhabitants of such 
worlds whether the orbs they live on circulate in orderly 
paths around some particular sun of the system, or travel 
now for a while round one, then around another, wandering 
from sun to sun, even as astronomers suppose that the 
comets have wandered which come from out the inter- 
stellar spaces to visit our solar system. 

Of course it would be idle to attempt to form any 
idea of the nature of beings inhabiting such worlds. It 
is quite out of our power to judge in what way the in- 
conveniences which we should certainly experience in 
these regions may not only be altogether obviated, but re- 
placed by advantages of which we can form no conception. 



A Chester of Sims. 217 

We can, however, form some idea of the wonderful 
scene presented to the inhabitants of such a world, be- 
cause in reality it is no other than that which would be 
presented to ourselves if all the stars seen on the darkest 
and clearest night were to grow suddenly in lustre until 
the faintest shone with light enough alone to banish 
night. The wonderful scene thus presented must be 
carried round by a stately motion of rotation precisely as 
happens with our own star sphere. Suns must be always 
rising and always setting, only the magnificent colours 
which adorn our skies at sunrise and sunset must be want- 
ing there, banished by the excess of splendour. It is 
manifest that, at least when the sky is clear, there can be 
no shadows in the landscapes on those distant worlds, 
since every quarter of the sky must have its suns. When 
the sky is partially clouded, there will be shadows, though 
not well defined shadows such as we recognise, but rather 
the lightest possible shade on those sides of objects which 
lie towards the clouded portion of the sky. 

But there is one circumstance in the condition of the 
inhabitants of these worlds which is not only interesting 
but instructive. Doubtless there are among them reason- 
ing beings who are led to enquire into the nature of the 
universe. In pursuing this enquiry they must in the first 
place encounter precisely the same difficulties which our 
terrestrial astronomers have met with. Each world must 
seem to the ordinary senses of its inhabitants the centre 
of the universe — the largest, finest, and most important 



2 1 8 The Expanse of Heaven. 

of all created objects. But doubtless the careful study of 
the motions of the heavenly bodies has led many races of 
reasoning creatures in worlds placed amidst the star- 
clusters to the conclusion that the seemingly small orbs 
which shine in their skies are much larger than the worlds 
they inhabit ; and we may readily believe that in some 
cases these beings have been able to form just ideas of the 
system or scheme of suns forming the star-cluster they 
belong to. 

But here their researches into the extent of the universe 
must certainly cease. For the blaze of light from the 
thousand thousand stars of their firmament must blot out 
all light from beyond. Their whole sky — by which I 
here mean the illuminated air which in the case of our 
own daylight limits our range of view, and forms a veil 
beyond which we cannot penetrate — their whole sky must 
be far more resplendent than ours, because every part has 
its hundreds on hundreds of suns. In this great splendour 
exists a perpetual limit to all extension of their researches 
into the constitution of the universe. The light of their 
myriads of suns blinds them to lights which lie beyond : 
their system of suns is their universe; and though the 
universe thus revealed to them is magnificent and stupen- 
dous, yet we can see how minute it is compared with what 
is revealed to ourselves, when we remember that we can 
perceive many hundreds of such systems of suns. 

Thus we learn how an excess of light may hide more 
than it reveals. We mav picture the inhabitants of worlds 



A Cluster of Suns. 2 1 9 

in some glorious star-clusters rejoicing in their knowledge 
of the splendour and extent of their sun system, all un- 
knowing of the far greater glories which the perpetual 
light of their skies conceals from them ; even as the 
man of science who trusts to science alone is too apt 
to glory in what is known, forgetful how the pride of 
material knowledge may blind him to far more important 
truths. Light is good, and science is good, but not all 
knowledge comes either with the light of day or with the 
light of man's unaided reason. Night has its revelations, 
more wonderful in reality though less splendid in seeming 
than the sun which rules the day. A true poet (though 
one that sang not often) has well said — 

Mysterious night ! when our first parent knew 
Thee from report Divine, and heard thy name, 
Did he not tremble for this goodly frame, 
This glorious canopy of light and blue ? 
Yet, 'neath a curtain of translucent dew, 
Bathed in the rays of the great setting flame, 
Hesperus with the host of evening came, 
And lo ! creation widened in man's view ! 
Who could have thought such darkness lay concealed 
Within thy beams, sun ! or who could find, 
Whilst fly and leaf and insect stood reveal'd, 
That to such countless hosts thou mad'st us blind ! 
Why do we then shun death with anxious strife ? 
If light can thus deceive, why may not life ? 



220 The Expanse of Heaven. 



WORLDS RULED BY COLOURED SUNS. 

In the heavens there are stars of many colours ; for one 
star differeth from another in glory. But the colours we 
see with the unaided eye are far less beautiful and less 
striking than those which are brought into view by the 
telescope. And among the coloured stars seen by the 
telescope there are none more beautiful than the coloured 
pairs of stars. Amongst these we find the most strongly 
marked contrasts — such combinations as green and red, 
orange and blue, yellow and purple ; then, again, we 
sometimes see both the companions of the same colour ; 
and yet again we find combinations where the contrast, 
though not so striking as in the pairs first mentioned, is 
nevertheless exceedingly beautiful, as when we have gold 
and lilac, or white and blue, or white and green stars ; 
and, lastly, we find among the smaller companions of 
double stars such hues as grey, fawn, ash-coloured, puce, 
mauve, russet, and olive. 

It was long thought that at least the more strongly 
marked colours, in the case of small companion stars, 
were due merely to contrast. Thus, if the larger of two 



Worlds Ruled by Coloured Suns. 221 

stars were orange, the smaller if really white would look 
blue, as anyone will perceive who will place on a sheet of 
dark paper a large orange-coloured wafer and close beside 
it a small white one. In like manner, if the larger star 
were red, the smaller would look green ; if the larger 
were yellow, the smaller would look purple ; and vice 
versa : only I may as well remark here that while the 
larger star of a pair is often red, orange, or yellow, it is 
never blue, green, or purple — at least, such colours are 
never strongly marked in any leading star of a pair or in 
any single star. 

But the supposition that the colours seen in double 
stars are due to contrast has been in several instances 
completely disposed of, by so arranging matters that one 
star only of a pair is seen at a time. This can readily be 
arranged where the stars are not very close, and in a great 
number of cases it has been found that the small star, 
seen alone, was really blue or green or purple, as the case 
might be. The experiment was in one case tried in the 
case of a very close pair, in a very interesting way. The 
star in question is the ruddy Antares, called also the 
Scorpion's Heart. This star has a minute green com- 
panion, far too close to the red primary star to be seen 
alone by any arrangement of the telescope. But advantage 
was taken by an eminent observer of the passage of the 
moon over this star. In a moment or two the moon hid 
the larger star, leaving the other shining alone, and then 
it was seen that the small star was unmistakably green. 



222 The Expanse of Heaven. 

The colours of the double stars, then, are real, so that 
if we could pay a visit to one of these pairs we should 
find coloured suns — red, orange, and yellow ruling suns, 
and green, purple, or blue minor suns, or, as the case 
might be, lilac, puce, mauve, russet, or olive suns of the 
smaller sort. Nor must we think of these smaller suns as 
really small in themselves* It is only by comparison 
with the leading orbs of unequal pairs that the lesser is 
called small. In reality it is probable that many of the 
lesser suns of these double systems are very much larger 
than all the planets of the solar system together. 

But before proceeding to consider the state of affairs 
in worlds governed and illuminated by double suns, a 
point as to the colour of these suns has still to be 
considered. I have said that the colours are real; but it 
is to be noticed that there are two ways in which this 
may be explained. The light of a star may be actually 
coloured ; or it may be white, but shine through some 
coloured transparent substance. We may take for illus- 
tration of a coloured light of the former kind the red 
fire, blue fire, and so on, of fireworks. Here the light is 
really coloured. As an illustration of coloured light of 
the second kind we may take red and green railway 
signals. Here we have lights which in one sense may be 
said to be really coloured, since their colours are not due 
to contrast or imagination or any like cause. Yet we 
know that the light is really white, and only appears red 
or green according as it shines through red or green 



Worlds Ruled by Coloured Sims. 223 

glass. Now, it is manifestly a very interesting question 
to decide whether the colours of the double stars are to 
be explained in one way or the other. Of course we 
know that the coloured stars are not shining through any 
substance resembling glass. But since it has been ascer- 
tained that the light of every star in the heavens (at least 
every star yet tested) shines through vapours which must 
to some degree modify its colour, the question is naturally 
suggested that in the case of the very marked colours of 
certain double stars the real cause of the colour is to be 
sought in the nature of the vaporous envelope. 

This has, in effect, been found to be the case in the few 
instances where it has been possible to try the experiment. 
It will not be difficult to convey an idea of the general 
principle on which the enquiry depends. When we 
examine the light of a star through a series of properly 
arranged prisms of glass, we get a rainbow-tinted streak 
of light, as in the case of the sun, only of course very 
much fainter. Also, precisely as in the case of the sun, 
the star's rainbow-tinted streak — or spectrum, as it is 
called — is crossed by a multitude of dark lines, which we 
know to be due to the presence of a number of vapours in 
the atmosphere of the star. Here I used the word atmo- 
sphere, but the reader must not fancy I mean anything 
resembling our own air. 

Every one of these stars has an amazingly complex 
atmosphere of glowing vapours, so intensely hot that 
such substances as iron, copper, and zinc are not merely 



224 The Expanse of Heaven. 

melted, but turned into vapour. Now, all stars are not 
alike as respects these vaporous envelopes. Some have 
substances in their atmosphere which others have not. 
And, again, some have apparently a much greater propor- 
tion of some substances than of others. Accordingly the 
dark lines across their spectra are differently arranged. 
Some have many dark lines in the redpart of the rainbow- 
tinted streak, so as in fact to have a great part of the red 
light cut off, and to shine therefore with a superabun- 
dance of the yellow, green, and blue. Such stars have a 
greenish light. Others have most of their dark lines in 
the yellow, and so assume a purplish colour. And others 
have most of their lines in the blue part of the rainbow- 
tinted streak, and so shine with an orange light. And of 
course it happens in many instances that the dark lines 
are spread with tolerable uniformity over the whole 
length, or the greater part, of the rainbow-tinted streak. 

The reader will see at once that the method of obser- 
vation here indicated supplies the means of answering the 
question whether the colours of the double stars are inhe- 
rent or caused by the absorbing action of the vaporous 
envelopes surrounding these stars. The process has been 
applied very successfully to a beautiful double star called 
Albireo, or Beta Cygni (that is, the second star of the 
Swan). This star is seen, even with a small telescope, to 
be double, and one of the stars, the brightest, is orange, 
while the other is of a beautiful blue colour. Now, when 
Dr. Huggins, the eminent spectroscopist, examined the 



Worlds Ruled by Coloured Suns. 225 

spectra of these two stars, he found that whereas in 
the case of the orange star there are several strong dark 
lines in the blue part of the rainbow-tinted streak, in the 
case of the blue star there is quite a cloud of fine lines in 
the red and orange portions. Hence we learn that the 
two stars owe their colour to the nature of their vaporous 
envelopes. Each star glows in reality with a white light ; 
but the white light has in one case to pass through 
vapours of a somewhat ruddy hue (because absorbing blue 
light), and therefore this star looks ruddy, while the light 
of the other star shines through bluish vapours, and there- 
fore this star looks blue. 

We do not yet know how it chances that the vaporous 
envelopes of these stars, and of other pairs of stars, differ 
in this way. Perhaps we shall never know. It is, how- 
ever, an important gain to our knowledge to have ascer- 
tained that the colours of the double stars are not 
inherent, but that these stars are, as it were, celestial 
signal lamps, shining through coloured matter. 

And now let us turn our thoughts for a brief space to 
the consideration of the state of the worlds circling around 
coloured pairs of suns. It is not quite clear what sort 
of arrangement would commonly prevail — whether such 
worlds would circle round the pair, travelling outside both, 
and having as the true centre of their motions the centre 
of gravity of their ruling pair of suns, or whether each sun 
of the pair would have its own family of dependent 
worlds. It may be that both arrangements would 



226 The Expanse of Heaven 

sometimes prevail in one and the same system. To show 
how this might be, we may conceive the following modi- 
fication of the solar system. 

Suppose Jupiter somewhat larger than he is, and at- 
tended upon by a larger and more important scheme of 
worlds. Also suppose Jupiter to be a subordinate sun — 
blue, green, or purple, as may best please the imagination. 
Then the other planets would be regarded as the sun's 
family, and of these, four — Mercury, Venus, the Earth, 
and Mars — would revolve as now around the sun, and 
within the path of Jupiter, his companion sun ; the other 
three — Saturn, Uranus, and Neptune — would revolve out- 
side both the pair of suns ; and, lastly, there would be a 
scheme of worlds circling specially around the smaller of 
the two suns. 

In some cases, however, very different arrangements 
would be requisite for the stability of the system. For in 
our illustrative case Jupiter travels nearly in a circle round 
the sun ; but some of the double stars move on very 
eccentric paths. Now, when the smaller star of the pair, 
travelling along with a family of dependent worlds, came 
sweeping close round the leading star, it would not only 
be exceedingly probable that some of the family would be 
left behind owing to the superior attractive power of the 
chief sun, but it would certainly happen that all the 
creatures living on the worlds thus brought into unusual 
proximity to a sun much larger than their own would 
suffer seriously, unless the family of worlds belonging to 



Worlds Ruled by Coloured Suns. 227 

the smaller sun were close to their own ruler. To use Sir 
John Herschel's expressive words, ' unless closely nestled 
under the protecting wing of their immediate superior, the 
swoop of their other sun in its perihelion passage round 
their own might carry them off, or whirl them off into 
orbits utterly incompatible with the conditions necessary 
for the existence of their inhabitants.' We may well 
agree with what Herschel proceeds to say, that 6 we have 
here a strangely wide and novel field for speculative 
excursions, and one which it is not easy to avoid luxu- 
riating in.' 

In whatever way the systems depending on double 
suns are arranged, this at any rate is certain, that the 
beings inhabiting any world in any one of these systems 
have two suns. There may be, and in many cases there 
must be, a great inequality between the apparent size and 
brightness of the two luminaries, but we cannot question 
that even the lesser (in appearance, as viewed from any 
particular part of a double sun system) must be a veritable 
sun. 

Taking the lesser suns of an unequal pair as seen from 
the earth, it must be remembered that that orb which 
looks so faint is in reality glowing with so great an inten- 
sity of heat and inherent lustre, that its light has passed 
to us after travelling over the tremendous abysses that 
separate us from the fixed stars. It is not an opaque orb 
shining by reflected light, but a mass of matter instinct 
with fire. We know this from its spectrum, which shows 



228 The Expanse of Heaven. 

that in its atmosphere are the vapours of elements which 
our fiercest furnaces can only liquefy. If, then, we could 
approach that self-luminous orb, we should find long 
before we reached the confines of its system that it is a 
true sun. And within its system — as seen, in fact, from a 
distance which, though enormous, is reduced to absolute 
nothingness when viewed from our enormous distance — 
it is certain that the star is a sun in this sense, that it is 
capable of dispelling night, that when it is above the 
horizon of any world having airs like ours there must be 
a glowing sky like that which, during our own day, hides 
the stars from our view. 

Thus every one of the worlds, in systems belonging to 
a double star, has a quadruple alternation, in place of that 
double alternation which we call day and night. There 
is, first, 'double day,' when both suns are above the 
horizon ; next, single day with one sun ; then, single day 
with the other sun ; and, lastly, true night when both suns 
are below the horizon. 

In my next I shall consider some of the results which 
must follow from these singular vicissitudes as well as the 
peculiarities of scenery, &c, which must prevail in worlds 
circling around coloured double stars. 



WORLDS LIT BY COLOURED SUNS. 

I will consider, first, the case of a world circling as our 
earth does in her orbit, but around a sun of a rich 
orange colour, while a companion sun of a blue colour 
travels around the same sun l on a path resembling that 
of the planet Jupiter. The blue sun would be a large 
and brilliant orb, as seen from the world whose condition 
I propose to describe ; but the orange sun would neces- 
sarily be far more brilliant and look far larger, being in 
reality the larger sun, and also the nearer. We will 
assume that the world we are considering has a moon 
somewhat like our own, and we may reasonably imagine 
that several other planets travel around the orange sun, 
others around both suns (that is, outside the path of the 
blue sun), and that, again, the blue sun has several 
planets travelling in immediate dependence upon it. 

Now, in the first place, let us take the case where the 
world is between the orange sun and the blue one, and let 
us suppose that the season corresponds to our spring. 
Then it is manifest that since one sun illumines one side 

1 Speaking exactly, we should say that the two suns circle around their 
common centre of gravity ; but here I deem it sufficient to use such expres- 
sions as accord best with ordinary modes of speaking. 



230 The Expanse of Heaven. 

of the globe, and the other illumines the other, there can 
be no night ; it is orange day to one half of the world, 
and blue day to the other. Moreover, since the season 
corresponds to our spring time, it follows that orange day 
lasts exactly as long as blue day, and using for con- 
venience the division of the day into twenty-four hours 
(which mayor may not be nearly the same as our ter- 
restrial hours), there are, all over the world, twelve hours 
of orange day and twelve hours of blue day. This, how- 
ever, would not last very long, any more than on our own 
earth we have Jupiter visible all night for any length of 
time. The blue sun would gradually take up the position 
which Jupiter has when he is an evening star. 1 

Now, we can easily see what would follow from this. 
The blue sun would, in fact, rise before the orange sun 
had set. Thus there would be orange day as before, but 
towards orange sunset there would be two suns, the orange 
sun nearing the west, the blue sun passing over the 
eastern horizon. Then would come orange sunset and 
blue day ; but the blue sun would set before the orange 
sun rose, and there would be therefore a short night, 
though no doubt not a dark night, since there would 
be blue twilight in the west and orange twilight in 
the east. Gradually the length of this night would 
increase, the length of the double day .also increasing, 
but the orange and blue hours gradually shortening. At 

1 This would happen at least if the blue sun were going the same way 
round the orange sun that the planet was going. 



Worlds Lit by Coloured Sttns. 231 

length the blue sun would have drawn quite near to the 
place of the orange sun in the heavens, and there would 
be double day and night, but neither orange day nor blue 
day alone. The double day would probably be white, 
since the colours of the two suns are supposed to be com- 
plementary. After this the blue sun would pass to the 
other side (the west) of the orange sun, and would be 
placed like Jupiter when he is a morning sun. There 
would then be blue morning, white day, orange evening, 
and night, the night gradually growing shorter and 
shorter, until at length the blue sun would be opposite 
the orange sun, and there would be no night, but simple 
alternation of blue day and orange day, as at first. 

I have not, in following these changes, taken any 
account of the varying seasons, because except when the 
two suns are together or opposite to each other, the 
considerations involved become rather more complicated 
than is desirable for these pages. But I will now, with- 
out following the blue sun round again, consider the effect 
of seasonable peculiarities when the two suns are on 
opposite sides of the earth. (When the two suns are 
together, the effects are of course the same as those 
recognised in our ordinary seasons.) Now, first, be it 
noticed that whatever be the pose of the earth, if the 
two suns are on opposite sides of her there cannot be any 
night, since one sun must illumine one half, the other sun 
illumining the other. But, whereas when the earth is 
posed as our earth is in spring, or autumn, there is 



232 The Expanse of Heaven. 

everywhere equal orange day and equal blue day, this is 
not the case at other times. 

Thus suppose the northern pole bowed towards the 
orange sun, as the northern pole of our earth is bowed 
towards our sun in summer, then in northern regions 
there is a long orange day, and a short blue day, and the 
reverse in southern regions. All round the northern 
pole — that is, within the regions corresponding to our 
Arctic regions — the orange sun does not set and the blue 
sun does not rise throughout the twenty-four hours; 
while in the corresponding southern regions the blue sun 
does not rise, and the orange sun does not set. At the 
equator, however, orange day and blue day are equal. Of 
course air is reversed when the southern pole is bowed 
towards the orange sun. 

But now let us consider how curiously the moon of 
our imagined earth must vary in aspect. I will consider 
just a few cases to show how wonderfully complex and 
beautiful must be the variations of a moon belonging to 
a double sun system. 

Suppose the two suns on opposite sides of the earth. 
Then it is clear that the moon's globe must (precisely 
like the earth's globe) have one half lit up by orange 
light, and the other half by blue light. Now the orange 
half will pass through all the phases that our own white 
moon exhibits. lb will be in turn round, half-full, 
gibbous, full, gibbous again, half-full, round, and new. 
But the part of the moon which with us appears dark, or 



Worlds Lit by Coloured Suns. 233 

wanting, will be blue. Probably, as there will be no 
night, the moon thus coloured will not be at all con- 
spicuous ; yet it is not likely to be so faintly seen as our 
moon is in the daytime, simply because the peculiarities 
of colour must render it easily distinguishable from small 
clouds. 

But next take the case where the blue moon is half- 
way round towards the place of the orange moon. Then 
the moon will have one half lit up by orange light and 
another half (not the opposite half) lit up by blue light ; 
these hemispheres of her surface will overlap equally, so 
that half of each will be lit up both by blue and orange 
light. Thus in fact the moon's globe will be divided into 
four equal parts (like four quarters of an orange), one of 
which will be orange, the next black, the next blue, and 
the fourth white. How singular must be the aspect of a 
moon so illuminated, as it passes through the ordinary 
lunar phases with respect to either sun, on the skies of 
the earth whose condition we are endeavouring to picture ! 

Very singular also must be the aspect of the different 
planets which are variously illuminated by the orange 
and blue suns. Instead of shining as the planets of the 
solar system shine, with a nearly constant colour — their 
own inherent colour — the planets of a double sun system 
must vary in aspect according to their positions with 
respect to the two suns which illuminate them. 

There is but one circumstance in which the celestial 
scenery presented to ourselves surpasses that which must 



234 The Expanse of Heaven. 

be exhibited to the inhabitants of such a world as we 
have been considering. The glories of the star depths 
are seldom seen from such a world ; night is the excep- 
tion, and often for many weeks in succession there can be 
no real night, but an alternation of coloured days scarcely 
separated by brief periods of coloured twilight when the 
orange and blue suns are but slightly below opposite 
horizons. It may be that on this very account night, 
being rare, is more valued, and the magnificence of the 
night sky more imposing than with ourselves. But it is 
a strange thought that the astronomers of those distant 
worlds — for such worlds we must believe there are — may, 
in their zeal for science, undertake long journeys to obtain 
move night during which they may study the wonders of 
the starlit heavens. 

Then, again, how wonderful must be those more special 
phenomena which correspond to our eclipses of the sun 
and moon, but are produced when one sun eclipses the 
other, or when one sun is eclipsed by a moon while the 
other sun is above the horizon, or when a moon is 
eclipsed as respects one sun while illuminated by the 
other! How strange the gradual change from white 
light to blue light as an eclipse of the former kind 
proceeds ; or from orange to blue light, or from blue 
light to orange, as the moon conceals one or other 
luminary ; while, when the moon is shining with white 
light produced by the combined lustre of the two suns, 
how strange must be the gradual appearance of a blue or 



Worlds Lit by Coloured Sims. 235 

orange shadow, according as the earth cuts off from the 
moon the light of the orange or blue sun ! 

And this leads us to consider the strange aspect which 
must be presented by ordinary objects — mountains, hills, 
buildings, plants, animals, and so on — when the two suns 
are both above the horizon. Where the light of both 
suns is falling there must be white light, or rather 
objects must appear, as they do in the white light of our 
own sun, with their natural colours. But parts which are 
in the light of but one of the two suns must show the 
colour of that sun, combined of course with their natural 
colour. There will only be true shadow where neither 
sun sheds its light. Or we may say that every object will 
throw a blue shadow opposite the orange sun, and an 
orange shadow opposite the blue sun, and that the part 
where the two shadows cross will alone be in true shadow. 
It will be manifest that natural scenery must present 
many beautiful varieties of effect altogether unfamiliar 
to us terrestrials, who know of no colours in scenery except 
those inherent in the objects themselves which form the 
landscape. Living creatures also must present a singular 
aspect, and to our conceptions an aspect not altogether 
beautiful, but too much like harlequinade to accord with 
terrestrial tastes. 

The skies, however, must be often exceedingly beauti- 
ful. Our clouds have their silver lining, because it is the 
white light of the sun which illumines them. Our summer 

sky presents glowing white clouds to our view, and at 
11 



236 The Expanse of Heaven. 

other times we see the various shades between perfect 
whiteness and an almost black hue, corresponding to the 
various degrees in which the illuminated side of a cloud 
is turned towards us. But imagine how beautiful the 
scene must be, when those parts of a cloud which would 
otherwise appear simply darker, shine with a fuller blue 
light or (as the case may be) with a fuller orange light. 
How gorgeous again must be the colouring of the clouds 
which fleck the sky when one or other sun is setting ! At 
such times on our earth we see the most beautiful tints, 
owing to the various degrees in which the atmosphere 
afreets the light of our single sun ; but how wonderful 
must be the varieties of colour when, in addition to this 
cause of varying tints, there is a sun of complementary 
colour illuminating those parts of each cloud which would 
be simply dark were there no other sun but the orb 
which is actually setting ! 

I have, however, taken but the case of a single world 
in a particular double sun system, and I have considered 
but few of the various relations presented by the skies of 
such a world. The actual varieties of appearance even 
in one such world must be almost infinite. Then in each 
double sun system there are several orders of worlds, 
even as in our solar system there are major and minor 
planets, asteroids, satellites, and so on, to say nothing of 
comets and meteor systems. Doubtless the several members 
of each order are as wonderful in variety of structure and 
condition as the several members of our solar system. 



Worlds Lit by Coloured Suns. 237 

Again, there are infinite varieties of arrangement depend- 
ing on the relative dimensions of the suns of a double 
system, as well as on the shape of the paths they pursue : 
and in their colours again there are many varieties, as 
mentioned in my last paper — yellow and purple suns, red 
and green suns, equal suns of golden yellow, cream white, 
rose colour, and so on, companion suns of lilac, russet, 
citron, fawn, buff, and olive hue, in endless numbers. 

Let it not be forgotten, in conclusion, that though there 
may be no world precisely like the one I have imagined, 
there must be many globes in double star systems where 
scenes very like those I have described are presented ; and 
that an almost infinite variety of arrangements must 
prevail among the thousands on thousands of such systems 
which astronomers have discovered. I conceive that few 
thoughts can be more striking and instructive than those 
suggested by this infinite wealth of beauty and variety. 
We see throughout the whole universe the same splendour 
on a large scale which is bestowed on a small scale upon 
the flowers of the field, which ' toil not, neither do they 
spin, yet Solomon in all his glory was not arrayed like one 
of these.' 



238 The Expanse of Heaven. 



TEE KING OF SUNS. 

When we learn how enormously the sun surpasses all the 
members of the planetary family in bulk and mass, and 
how vast is the power represented by his light and heat, 
the idea is naturally suggested that the sun is either the 
leading orb in the universe or at least co-equal with those 
other suns the stars which exist in such countless numbers 
throughout space. It is sufficiently amazing to conceive 
that that glorious orb which astronomy pictures the sun to 
be, the scene of processes so stupendous, of outbursts so 
overwhelming, girt about by the wonderful corona and 
zodiacal light, attended on by a scheme of worlds among 
which our earth is but an insignificant body, and so 
mighty as respects attractive power that matter drawn to 
his surface from outer space reaches him with a velocity 
of nearly 400 miles in a second, should be repeated (as it 
were) hundreds and thousands and millions of times within 
the sidereal universe. But what is this thought even, 
amazing though it seems, to the consideration that our 
sun is not only inferior to a few suns, here and there, but 
actually belongs to an inferior order of suns; that the 
class to which he belongs bears to the chief known order 
of suns a relation as inferior as that of our earth and her 



The King of Stms. 239 

fellow terrestrial planets to the giant orbs, Jupiter and 
Saturn, Uranus and Neptune, which circle outside the 
zone of asteroids ? 

Such, however, is the result to which scientific re- 
searches tend. I am not about to present the full evi- 
dence for the general statement I have just made, reserv- 
ing the point for another article. What I now propose is 
to compare, so far as comparison is possible, a number of 
the leading order of suns — the white stars — with our sun, 
a member of the second order of suns — the golden yellow 
stars. I am about to describe what is known about the 
glorious star Sirius — the blazing Dog Star of the ancients. 
I speak of this star as the King of Suns, not as assuming 
that he is indeed the largest sun in the universe, but 
because he is the brightest star of his order visible to us, 
and the only sun in the universe of which it has been de- 
monstrated that, taking light as the measure of magnitude, 
he surpasses our sun at the very least one thousand times 
in volume. * 

But how, it may be asked, can we estimate the magni- 
tude of a star from its brightness, or, indeed, form any 
idea as to the dimensions of a body which even in the 
most powerful telescope appears as a mere point ? For 
this is indeed the case with Sirius, notwithstanding the 
fact that in a powerful telescope we seem at a first view 
to see in this star a bright glare covering a considerable 
space. Attentive scrutiny soon reveals the fact that the 
glare is a merely optical phenomenon, and that the true 



2 4-0 The Expanse of Heaven. 

image of the star is a very bright point of light. It is 
clear that if by any increase of optical power we could see 
a star with a measurable disc, we should only need to know 
the star's distance to infer the real dimensions of its 
globe. But we can see no disc, and except in the case of 
about a dozen stars, we cannot measure star-distances, and 
only know that the stars lie beyond that distance which 
our instruments are capable of measuring. How, then, can 
we form an opinion as to real star magnitudes ? 

I proceed to explain what has been done towards the 
solution of this difficult problem, noting that if the reader 
should be dissatisfied with the nature of the evidence, he 
must bear in mind that the astronomer has no choice but 
to deal with the evidence supplied to him. It would be 
very convenient if he would invent evidence, and he might 
in this way give a much more striking and satisfactory 
account of the mysteries of the star depths. But what we 
want is the truth ; and the truthful astronomer must often 
be content to give that answer which was the favourite 
reply, we are told, of the eminent French mathematician 
Lagrange, c I don't know.' l 

1 This answer is not so favourably received, in general, as it should be. I 
remember how on one occasion I was asked at the close of a lecture on the star 
depths why I had not told my audience the true shape of the sidereal uni- 
verse — that is, its relative length, breadth, and depth. I replied in effect 
that before I could give this information I must first possess it myself, and 
that as yet no man possessed it. I could perceive that the audience were 
very far from satisfied with this reply. But I might have occasioned even 
more dissatisfaction if I had said, what is in all probability the real truth, 
that not only is man now ignorant of the configuration of the sidereal uni- 
verse, but he can never hope to attain exact knowledge on the subject. 



The King of Suns. 241 

To determine the distance of an inaccessible object we 
must compare the direction in which it lies as seen from 
two stations sufficiently far apart. This, which is a prin- 
ciple of ordinary land-surveying, is equally true of the 
celestial objects. The astronomer determines the moon's 
distance by observing her from the northern and southern 
hemispheres, as from the Greenwich Observatory and the 
observatory at Cape Town ; or else he takes advantage of 
the fact that the earth rotates on her axis, and so carries 
any given station from one side to another in a given 
time. The distance of the sun can be measured in no 
other (direct) way, and although we hear of the transits of 
Venus as means of which the astronomer avails himself to 
determine the sun's distance, yet the very same principle 
is involved — the value of a transit of Venus depending 
solely on the fact that the observers at two distant 
stations can in point of fact regard her as a celestial 
index, traversing the sun's face as an index plate, so that 
they possess, as it were, an instrument of survey more 
powerful than any terrestrial instrument. 

To measure star distances the earth's dimensions are 
altogether too small. No instrument which man will ever 
make would show the slightest difference in the direction 
of any star as seen from opposite sides of the earth. But 
precisely as the measurer of the moon's distance need not 
leave his observatory, or have a companion observer 
working at a distant station, if he prefers to trust to the 
earth's rotation to sway his station from one side to the 



242 The Expanse of Heaven. 

other — so the astronomer, unable to leave the earth to 
seek, as he would wish, a station millions of miles away, 
can nevertheless avail himself of the earth's motion of 
revolution around the sun, which in the course of six 
months will carry the earth from one side of her path to 
the opposite side, one hundred and eighty-three millions 
of miles away. One place and the other (any two 
opposite points of the earth's orbit) may be regarded as 
two observing stations at the ends of a base line of this 
enormous length, laid down, as it were, to extend astro- 
nomical survey from the solar system to the stars. 

It might be thought that this base line could not but 
be amply sufficient for the purpose in view. But so much 
vaster are the distances of the stars, that until quite recent 
years tins base line proved altogether too short for effec- 
tive measurements, and even now only one star has had 
its distance fairly measured, wdiile some nine or ten have 
had their distances roughly estimated. All the rest which 
have been tried lie so far beyond our means of measure- 
ment as to show no signs whatever of change of place as 
the earth circuits around that orbit which to our concep- 
tions seems so enormous in extent. 

Now, the one star w T hose distance has been measured — 
Alpha Centauri — is found to lie more than 200,000 times 
farther away than the sun. Moreover, the light of this 
star lias been compared by means which need not here be 
described with the light that we receive from the sun, and 
has been found to be equivalent to about the 17,000 



The King of Situs. 243 

millionth part of the sun's light. But we can tell how 
much light we should receive from our sun if he were 
removed to 200,000 times his present distance. His light 
would be reduced not to the 200,000th part of its present 
amount, but to the 200,000th part of that reduced amount 
— or, in fact, to the 40,000 millionth part of his present 
lustre. So that he would shine much less brightly than 
the star Alpha Centauri if he were removed to the same 
distance. According to the best estimates of the star's 
distance, it must emit about three times as much light as 
the sun. 

But Sirius is much farther away than Alpha Centauri, 
and, moreover, shines much more brightly. Sirius is one 
of the nine or ten stars mentioned above as lying at 
distances not absolutely immeasurable. We cannot place 
much reliance on the results obtained in the case of Sirius, 
because his actual change of place as the earth circuits 
round the sun is so exceedingly minute. The best esti- 
mates assign to Sirius a distance exceeding that of Alpha 
Centauri five-fold — or rather that is the mean between 
the two best estimates. Taking this value, it follows that 
if Sirius shone no more brightly than Alpha Centauri in 
appearance, he must nevertheless give out twenty-five 
times as much light. But a careful comparison of his 
brightness with that of Alpha Centauri shows that he is 
about four times brighter. Therefore in reality he must 
give out about one hundred times as much light. 

We have seen, however, that Alpha Centauri gives out 



244 The Expanse of Heaven. 

about three times as much light as our sun. It follows 
that Sirius Bhines in reality three hundred limes more 
brightly than the sun. Now, this implies that if the 
surface of Sirius is of the same intrinsic brightness a* the 
sun's — that is, if on the average each Bquare mile of the 
surface of Sirius gives out the same quantity of light as 
each square mile of the sun's surface — then the surface of 
Sirius must be 300 times as large as the sun's. It would 
follow that the diameter of Sirius is between 17 and 18 
times as Large as the sun's. (For 17 times 17 are less 
than 300, and 18 times 18 are greater than 300.) Hence 
the volume of Sirius would be about 2,200 times as great 
as the sun s (this number 2,200 being obtained by multi- 
plying 500 by 17^, which is nearly equivalent to multi- 
plying 17* twice into itself). Tins is on the supposition 
of equal surface-lustre; and it cannot be regarded as 
certain that Sirius is not considerably brighter than our 
sun as respects Ids actual surface. Of course if tins is the 
case, we cannot assume that Sirius is larger in so great a 
proportion as when wo suppose his intrinsic lustre the same 
as the sun's. 

But it is worthy of notice that the eminent French 
physicist St. Claire Deyille considers it impossible that 
under any circumstances a surface can be much hotter or 
more luminous than the solar surface. We shall probably 
be within the limits of fact if we regard the surface of 
Sirius as not more than twice as bright as the sun's. 
This would leave his surface 150 times larger than the 



The King of Su 71s. 245 

sun's, or, for convenience of reckoning, Bay 144 times; liis 
diameter would tluis be twelve times the sun's, and Ins 

volume 1,728 times the sun's. 

Have I not rightly called Sirius a 'king of suns'? 
Prom that glorious orb, nearly 2,000 such orbs as the sun, 
that great and mighty globe, instinct with fire and life, 
might be formed, each fit to be the centre of a scheme of 
circling worlds as important as that over which our sun 
bears sway! And then conceive how vast must be the 
scale of the planetary scheme which Sirius doubtless rules 
over. Indeed, it must be vast for the mere security of* its 
inhabitants. An orb placed as far from Sirius as Mercury 
or Venus, or the earth or Mars from the sun, would be 
scorched with a heat so intense that no life would be 
possible upon it. The distance of Jupiter would be belter, 
but even there the supply of heat would be six times 
as great as that which we receive from the sun. At 
Saturn's distance a world would be illuminated and 

warmed half as much again as our earth. Only at a 
distance about one-fifth greater than that of Saturn, so 
long regarded as the most distant member of the solar 
family, would an attendant on Sirius receive the same 
supply of light and heat as we receive from the sun. In 
short, a scheme of planets bearing the same relation to 
Sirius as respects the supply of light and beat, which the 
planetary system bears to the sun, would have to be con- 
structed on a scale twelve times vaster. 1 

1 It would not ev<;n then resemblo the planetary system in other n- 
pocts ; for the light and heat and attractive energy of Sirius are reduced at 



246 The Expanse of Heaven. 

After all, however, the most wonderful circumstance is 
that of which alone we are certain. We know nothing of 
the family over which Sirius bears sway; but we are well 
assured as to his own splendour and surpassing volume, 
and these are the features which afford the most surprising 
evidence of the wonders of the star depths. 

In the next chapter, however, I shall have to consider 
yet greater wonders ; I shall have to deal not with a king 
among suns, but with an order of kingly suns. 

the square of the distance ; and to make them equivalent to those in the solar 
system we have supposed all the distances enlarged in the same degree as 
his surface exceeds the sun's. But his might is more probably proportional 
to his volume, in which case the attraction he exerts remains still twelve 
times greater in the corresponding planets of the imagined system than our 
sun's attraction on the respective members of his family. Therefore, unless 
we further modify our supposition, we must set all the Sirian planets 
circling much more rapidly than the corresponding members of the solar 
family. They must, in fact, move 3 \ times as fast, and therefore have years 
correspondingly shortened. Thus the one corresponding to our earth 
would have a year of about 104^ days, and the others in proportion. 



FOUR ORDERS OF SUNS. 

In my last chapter I described a sun — the star Sirius — 
so superior to our own in splendour, and doubtless in 
magnitude, that it must be regarded as belonging to a 
superior order. We might, indeed, if there were no 
evidence to the contrary, regard Sirius as the king of 
suns, not as a member of a higher order. We might 
suppose that he is perhaps the central sun of the star 
system, in which case his superiority over our own sun 
would not be surprising, since it would correspond pre- 
cisely with the superiority of the sun over the members 
of his planet family. Indeed, this view was adopted 
before it was known how enormously Sirius exceeds the 
sun in magnitude. The great German philosopher Kant 
regarded Sirius as the central sun of the universe, because 
it appeared to him from other considerations that the 
central sun should lie towards the region occupied by 
the constellations Orion, the Hare, and the Two Dogs; 
and Sirius being the leading star of that region (as indeed 
of the whole stellar heavens) appeared to Kant very well 
suited to be the ruling orb of the universe. 

But, apart from all other considerations, the enormous 
distance of Sirius shows conclusively that be cannot be 



248 The Expanse of Heaven. 

the orb which our sun obeys, far less the ruling orb over 
the stars lying far away beyond our sun towards the con- 
stellations Hercules, the Eagle, and so on, which occupy 
the region opposite to that in which Sirius is the leading 
orb. It requires no elaborate calculation to prove this. 
Eoughly speaking, Sirius is a million times farther away 
than the sun ; and since attraction varies as the square 
of the distance, his attractive influence is a million 
million times less than it would be if he were only at 
the sun's distance from us. Supposing his mass the 
2,000th part of the sun's, it follows that his influence 
on the sun is but the 500 millionth part of the sun's 
influence on the earth. 1 This would be altogether in- 

1 It may, perhaps, interest the reader to learn precisely what the in- 
fluence of the sun on the earth is, and so to infer the influence of Sirius on the 
sun. "VVe must of course consider equal quantities of matter, and for con- 
venience we will take that quantity of matter which we call a ton — that is, 
the quantity of matter which, placed on the earth's surface, weighs a ton, 
or produces that amount of downward pressure. Now, a ton of the earth's 
matter tends sunwards with a force only equal to that which would be pro- 
duced on the earth by the downward pressure of 1 lb. 3 oz. 200 gr., or 
roughly 8,500 grains (New Avoirdupois, which is the same as Troy measure). 
Accordingly, on our assumption as to the mass of Sirius, which is probably 
above his real mass, a ton of the sun's mass tends towards Sirius with a 
force corresponding to the 500 millionth part of 8,500 grains, or roughly 
the 59,000th part of a single grain. This is probably the greatest attrac- 
tion which any individual star exerts on our sun, and indicates the exceed- 
ing feebleness of the forces exerted on each other by the stars, regarding 
those forces as moving forces. The total quantity of attraction between 
Sirius and the sun is of course enormous, because the sun's mass is so 
enormous. But this total quantity is not what we have to consider in en- 
quiring into that star's fitness to rule our sun. For its magnitude, we see, 
depends on the sun's magnitude, and of course his magnitude gives him in- 
dependent power. In all such cases we have only to compare the attrac- 



Four Orders of Suns. 249 

sufficient to sway the sun appreciably from his course. 
If, indeed, there were no other bodies in the universe than 
the sun and Sirius, our sun would circuit around Sirius, 
though the period of revolution would be enormously 
long. But as it is the attraction of Sirius is only one 
among thousands of attractions, exerted by the leading 
neighbouring stars ; and the sun obeys the combined 
influence of these attractions, not the power of any 
particular star. Every other star also, including Sirius, 
is similarly influenced by the combined influence of all 
the rest. 

Still Sirius, for aught that has yet been shown, might 
be distinguished above all other suns, and his influence, 
though far inferior to the combined influences of other 
suns, might still be paramount in the sense of being far 
superior to that exerted within the universe by any other 
sun whatever. 

But we have now to consider evidence which points to 
Sirius as one only of a class or order of suns, and an order 
including a great number of stars. 

I have spoken in former chapters of the teachings of 
the spectroscope respecting the stars; and in so doing I 
have mentioned specially what has been learned in this 
way about the colours of the stars. It has been shown 

tions exerted on equal quantities of matter. Thus we may speak of Sirius's 
moving power on the sun as less than the moving power which our earth 
has on bodies near her surface (that by which she causes them to fall if 
unsupported), in the same proportion that the 59, 000th part of a grain is 
less than a ton, or roughly as 925,000,000,000 to 1. 



250 The Expanse of Heaven. 

that the light of every sun is that arising from the in- 
candescence (or whiteness) of matter intensely hot ; and 
that the colours of the stars originate in the gaseous 
envelopes surrounding the glowing core or heart of each. 
These envelopes are themselves intensely hot, glowing 
indeed with heat ; yet compared with the fierce heat of 
the matter they surround they may be regarded as re- 
latively cool. They possess, according to their constitution, 
the power of cutting off various parts of the light issued 
by the suns to which they severally belong. For the 
spectroscope spreads out that light for us into a long 
rainbow-tinted streak, and across that streak we can see 
the dark lines showing where light of this or that particu- 
lar colour is wanting, absorbed by some special vapour 
in the star's atmosphere. 

Now, I think it will appear very clear to the reader that 
if the stars really are of various orders, the spectroscope 
may probably possess the power of distinguishing one 
order from the other. A star very much larger and more 
massive than our sun should have, one would suppose, a 
different spectrum ; for it is difficult to imagine that 
under the very different attractiye power which such a 
globe would exert on its atmosphere the various vapours 
of that atmosphere would not be differently related to 
the glowing centre. 

For example, if hydrogen were present in the same 
relative proportion in the atmosphere of so massive a 
sun, we might imagine that this gas, being the lightest 



Four Orders of Suns. 251 

of all known gases, would be extended above all other 
vapours in the star's envelope, as we see in the case of 
our sun ; but also we should expect to find a much greater 
quantity of hydrogen outside the other envelopes of the 
larger star. And then the region where enormous pres- 
sure liquefied or solidified the core or crust of such a sun 
would lie relatively nearer the region where the hydrogen 
began to be mixed with other vapours. For light though 
hydrogen is, it would produce an enormous pressure in 
the atmosphere of so monstrous a sun as Sirius ; and at 
the bottom of the hydrogen envelope (pure or nearly 
so) there would be a much greater pressure than at 
the corresponding part of the atmosphere of our own 
sun. 

So that I think we should expect to find the hydrogen 
dark lines much stronger relatively in the spectrum of 
Sirius than in that of our own sun. And if this turned 
out to be the case, we should regard the peculiarity as 
characteristic of a very large sun ; and if other stars gave 
the same kind of spectrum, we should be led to believe 
that they were also very large suns. We should not be 
prevented from adopting this belief by the faintness of 
such stars, unless we knew their distance ; for they might 
be very much farther away than Sirius, and so rendered 
apparently faint, while really emitting as much light as he 
does. But our opinion would be very much strengthened 
if we found that the stars giving this particular spectrum 
included some of the brightest orbs in the heavens, orbs 



252 The Expanse of Heaven. 

also known to lie either at enormous estimated dis- 
tances, or so far away that all attempts to estimate their 
distance had failed. Our opinion would be still further 
strengthened — nay, I think it would grow into conviction 
— if we found that the stars giving this spectrum 
also showed a general resemblance to each other in 
tint. 

Now, this is precisely the evidence which we have on 
this matter. 

The star Sirius gives a spectrum ' crossed by four very 
strongly marked dark lines, which are those corresponding 
to the gas hydrogen.' Of six hundred stars examined by 
the Italian, astronomer Secchi, about three hundred were 
found to give a spectrum of this kind. Most of these stars 
are distinguished by their great brightness and by their 
somewhat bluish tint. The class includes Rigel, the 
bright star on the advanced foot of Orion ; Altair, the 
leading brilliant of the Eagle ; Wega, the splendid gem 
adorning the Lyre ; six of the stars of Charles's Wain ; and 
other bright luminaries. 

May we not infer with some confidence that these 
stars belong to a higher order than our sun — an order 
whose real importance is indicated by the demonstrated 
superiority of Sirius ? It is true that Sirius is the only 
member of the order whose real lustre relatively to our 
sun's has been estimated. But this is only because the 
other stars of the order lie too far away to give any 
measurable indications of their true distance, or therefore 



Four Orders of Suns. 253 

any means of estimating their real lustre. And even as 
it is we can indicate in the case of most of them a great 
superiority to the sun, our only difficulty being in de- 
termining how great that superiority is. Take Kigel, for 
example. This star shows no signs of displacement as the 
earth circuits on her wide orbit round the sun. We may 
safely assume, then, that this star is at least twice as far 
away as Sirius, which does show a measurable displacement. 
So that if Eigel were put where Sirius is, he would shine at 
least four times as brightly as at present. But this would 
make his lustre equal to two-thirds of that of Sirius, or his 
real brightness 200 times that of our sun. Taking his 
intrinsic lustre, mile per mile of surface, as twice our 
sun's, we find his surface 100 times our sun's, his diameter 
10 times, his volume and presumably his mass 1,000 times 
the sun's — at least, be it remembered. Precisely the 
same reasoning applies to Wega, whose distance has 
indeed been estimated to be twice that assigned to 
Sirius. 1 

We must not assume that because half the stars 
observed by Secchi gave this particular spectrum, there- 
fore half the suns of our universe are of the larger order ; 
for it must be remembered that the largeness and bright- 

1 By myself in my last chapter. There are in reality two estimates of 
the distance of Sirius, one by Henderson, the other by Cleveland Abbe. I 
take the mean of the two. It serves to show how extremely difficult all 
measures of such verj*iistant bodies must necessarily be, to mention that 
Abbe's measurement exceeds Henderson's as 5 to 3. This, however, does 
not affect the inference of enormous distance. 



254 The Expanse of Heaven. 

ness of these bodies render them more amenable to spec- 
troscopic investigation. 

It remains to be shown, however, that other stars pre- 
sent different appearances under spectroscopic analysis. 
The evidence on this point is very clear. About one-half 
of the three hundred remaining stars examined by Secchi 
were found to give a spectrum similar in character to 
that given by our sun, only of course very much fainter. 
Among the stars belonging to this class are Capella, 
Pollux, Dubhe in the Great Bear, Procyon, and others. 

But it is, perhaps, when we turn to Secchi's third 
order of stars that the most singular revelation awaits us. 
For he tells us that the stars of this order have a spectrum 
resembling that of a sun-spot ; and he infers that the 
stars of this order are covered with many spots. An in- 
teresting confirmation of this view presents itself. We 
know that the spots on the sun are variable. Sometimes 
there are many, sometimes few or none. Now, a sun 
much more spotted than ours ever is would be exposed to 
yet greater variations, insomuch that we should expect its 
light even to vary as a whole, and perhaps to a considerable 
extent. Now, Secchi's third order includes the most re- 
markable variable stars in the heavens : Mira, the Wonder- 
ful Star in the Whale ; Betelgeux, the singularly variable 
orange star, which is ordinarily the leading brilliant of 
Orion, but sometimes surpassed by unchanging Kigel ; and 
other variable orbs. 

A fourth order remains, respecting which I shall say 



Four Orders of Suns. 255 

little, because in point of fact little is known. It in- 
cludes about thirty of the stars observed by Secchi, chiefly 
inconspicuous orbs, but remarkable for their deep red 
colour. 

Such is the evidence thus far obtained by the newest 
instrument of science. 



256 The Expanse of Heaven. 



TEE DEPTHS OF SPACE. 

When we look around us into the regions which surround 
the solar system, and see the myriads of myriads of stars 
which are spread through space, it is impossible not to 
feel strongly the desire to penetrate the mystery of the 
star-strewn depths. We have learned much respecting 
the earth on which we live, and not a little of the system 
to which the earth belongs. We have at least so far 
solved the problems presented to us by the planetary 
scheme as to recognise the subordinate position which our 
earth holds within it, and that the sun is the mighty 
ruler whose sway guides all the planets in their courses. 
But the enquiring spirit of man is not satisfied with these 
discoveries. No sooner has he learned to regard the earth 
as but one of a system of worlds circling round the sun, 
and that that system has such and such proportions, and 
presents such and such forms of motion, than he^ desires 
to regard our sun as but one of a system of suns, and to 
ascertain what may be the nature and the scale of this 
higher system, what the movements taking place within 
it. This was the noble problem which the elder Herschel 
set as the great end and aim of all his labours : ' A 



The Depths of Space. 257 

knowledge of the construction of the heavens,' he said, 
towards the end of his wonderful career as an observer, 
* has always been the ultimate object of my observations.' 

It is in contemplating this problem that man is most 
forcibly taught the insignificance of the earth on which 
he lives — in point of size at least, though we must re- 
member that ' great and bright infers not excellence.' So 
long as the study of external nature is limited within the 
bounds of the solar system, we are able to measure not 
merely the proportions, but the dimensions of the objects 
we study, but so soon as we pass beyond our solar system, 
the power of measuring is wanting — or at least is so 
limited as to serve us but for a short distance. We have 
learned the distances of about half a dozen stars, and even 
those distances have been only roughly ascertained ; all 
distances beyond are immeasurable, and for the most part 
must remain so, it would seem, unless some hew method 
of estimating star distances should unexpectedly be dis- 
covered. 

We have to judge of the star depths around us, then, 
in some other way than by actual measurement. We 
must scrutinise them attentively and be on the watch for 
indications of various nature by which to form some idea 
of the laws of stellar grouping. 

To this problem few astronomers indeed have devoted 
their energies, probably because it presents difficulties so 
enormous. The elder and younger Herschel, William 
Struve, Madler, and one or two more, are all who can be 



258 The Expanse of Heaven. 

named as having actually taken these questions in hand 
as astronomers, though Kepler, Kant, Lambert of Alsatia, 
Wright of Durham, and a few others have speculated 
more or less ingeniously respecting the sidereal system. 

It is to the original mind of Sir W. Herschel that 
science owes the bold idea of gauging the star depths, of 
actually attempting to apply a measuring-line from our 
tiny earth by which to determine how far the stellar 
system extends in this direction and in that, until its 
whole figure should have been determined. The process, 
he suggested, might be compared to that by which the 
nautical surveyor charts the sea bottom, marking its 
depths and shallows, its hills and depressions, its peaks 
and mountains, its valleys and ravines. Precisely as the 
lead line of the seaman passes through more water where 
the depth is greater, and through less where the shallows 
lie, so Herschel conceived that the telescopic line of sight 
would pass through more stars where the stellar system 
has its greatest extension from us, and through fewer 
where the boundaries of that system are nearest to us. 

He threw out the visual plumbline again and again, 
now sounding, as he conceived, the profundities of the 
star system, and now finding that the limits of the system 
were relatively close to us. He found that when the 
line of sight was directed towards the zone of the 
heavens where we see the Milky Way, the telescopic field 
of view was nearly always rich with stars ; but when he 
turned his telescope away from that zone, and especially 



The Depths of Space. 259 

when it was turned nearly square to the general level of 
the Milky Way zone, few stars could be perceived. 

Accordingly, he concluded that the system of stars is 
flattened in shape, extending farthest where we see the 
Milky Way, and having boundaries which lie relatively 
close in, towards the parts of the heavens which lie 
farthest from the galactic zone. It was on this evidence 
that he based what has been called the 6 cloven flat disc ' 
theory of the sidereal system. For the Milky Way has 
two branches through a considerable portion of its circuit, 
so that the greatest extension of the star system lies 
towards two planes, where the Milky Way is cloven. A 
good general idea of the shape of the stellar universe 
according to these results may be obtained by taking two 
wafers, and after wetting one-half of one of them — that 
is, a semicircle of its surface — applying the other thereto, 
so that we have a double wafer; but one-half of the 
double wafer has its two leaves disjoined. Now, if these 
two semicircular portions be slightly separated from each 
other with the point of a knife, so that they slope away 
from each other, we have a figure something like the 
cloven flat disc of Herschel's theory. Only it will be 
understood, of course, that he did not suppose there was 
anything like regularity in the shape which at this time 
he ascribed to the stellar system. 

But as he went on with his observations, Herschel 

gave up the principle of star-gauging and its results. It 

is well to notice this carefully ; because the text-books of 
12 



260 The Expanse of Heaven. 

astronomy say little on the subject, and what they say is 
for the most part inexact. Herschel began to perceive 
that there are laws of physical association, binding the 
stars together in schemes subordinate to the stellar system 
regarded as a whole. And he came to regard the Milky 
Way itself as a subordinate system, or as at least distinct 
in character from the parts of the star system lying 
around us. He wrote thus in 1802, seventeen years after 
he had enunciated the cloven-disc theory. ' Although 
our sun and all the stars we see may truly be said to be 
in the plane of the Milky Way, yet I am now convinced 
by a long inspection and continued examination of it, 
that the Milky Way itself consists of stars very differently 
scattered from those which are immediately about us/ 
And again in 1811 he said, ' When the novelty of the 
subject is considered, we cannot be surprised that many 
things formerly taken for granted should, on examination, 
prove to be different from what they were generally, 1 but 
incautiously, supposed to be. For instance, an equal 
scattering of the stars may be admitted in certain 
calculations ; but when we examine the Milky Way, or 
the closely compressed clusters of stars, this supposed 
equality of scattering must be given up.' Now, it will be 
clear to all that the cloven-disc theory, and the principle 



1 It may be necessary to explain that the word ■ generally ' here does 
not refer to the number of those who have adopted the view referred to t 
Vuit to the general sense iu which the view had been adopted. No one can 
kmbt this who has read Hersehel's series of papers. 



The Depths of Space. 261 

itself of star-gauging, were necessarily based on a belief 
in the generally equable scattering of the stars. In 
giving up this belief as a general rule for guidance, 
Herschel was in effect giving up the hopes he had formed 
when he thought of the method of star-gauging, as well 
as all the general results to which he had been led by the 
application of that method. 

When Herschel was a very old man, close on the four- 
score years which so few attain without some signs of 
failing mental powers, he invented another method, 
commonly confounded in our text-books of astronomy 
with the method of star-gauging, but in reality quite 
distinct from it. In star-gauging he had estimated the 
distance of the boundary of the star system by the 
number of stars he could count in the telescopic field ; 
in the new method he estimated the distance of star 
groups by the telescopic power required to resolve them 
into separate stars. A group like the Pleiades, or like 
the Beehive in Cancer, which can be resolved into stars 
with a very small telescope, lies relatively near to us, 
according to this theory ; a group which can only be 
resolved with one of the mightiest of the telescopes which 
Herschel used lies very far away ; and some groups which 
none of his telescopes could resolve lie at distances incal- 
culable until some larger telescope can accomplish the 
resolution of the group. 

I shall not say much of this principle. I believe 
Herschel himself would have abandoned it had he lived 



262 The Expanse of Heaven. 

to test it thoroughly. A little consideration will show 
that it implies a uniformity of structure throughout the 
stellar system which is very little accordant with what 
Herschel had himself discovered while making those 
observations which led to the abandonment of the star- 
gauging method. It will presently appear that other 
and more decisive evidence of variety of structure has 
been obtained since Sir W. Herschel's time. 

The reader will begin to see the nature of the methods 
by which alone the astronomer can hope to penetrate the 
mystery of the star depths. Each of the methods just 
described must be regarded as a kind of survey of the 
heavens — not of the heavens presented to ordinary vision, 
but of the heavens brought into view by the penetrating 
eye of the telescope. For if the human eye could 
suddenly obtain the power of telescopic vision, those 
wealths of star-strewing which it is the province of star- 
gauging to measure would be revealed to our view, not 
piecemeal, as under telescopic scrutiny, but at once as in 
a grand celestial panorama. Those varieties of distribu- 
tion to which Herschel applied his resolution test would 
be clearly recognised. Here the stars would be seen 
spread richly over a region of the heavens, but clearly 
separated from each other ; elsewhere would be regions 
where the stars would more closely cluster, though still 
separately discernible ; but in parts of the heavens veri- 
table star-clouds would be seen, regions where the stars 
gather so closely together that even the enhanced powers 



The Depths of Space. 263 

of vision I have imagined — nay, though the power of the 
Bosse telescope had been acquired by man — would fail 
to show discrete stars, the sky in those part3 heing aglow 
with condensed star-light, on which, as on a splendid 
background, brighter stars would be seen spread with 
inconceivable richn 

Such a scene might not be intelligible at a first view ; 
it might even baffle all attempts at interpretation, all 
efforts to estimate the relative distances and proportions 
of its several parts. But our only path to the solution of 
the noblest problem in science is by presenting to the 
mind's eye such a picture of the great star-strewn sphere 
which surrounds us on all sides ; wdien that has been done, 
we shall begin to know whether the great problem is 
altogether beyond our mastery. 

Herschel'g two methods having practically proved 
insufficient, it remains to be seen by wdiat other methods 
we may render more distinct our mental picture of the 
star depths. 

It occurred to me very early in my enquiry into the 
great problem, and before I had fully investigated the 
long and noble series of researches by which Sir W. Her- 
schel had attempted to master it, that this was a case 
where the mental vision must be assisted by the bodily 
vision. It is singular that hitherto, so far as I know (and 
I think little that has been done on the subject has escaped 
my reading), the idea of picturing the results obtained by 
telescopic scrutiny had been altogether overlooked. I do 



264 The Expanse of Heaven. 

not here refer to pictures illustrating theories of the 
universe. Every student of astronomy knows that Sir W. 
Herschel was careful to give diagrams illustrating his suc- 
cessive conceptions of the structure of the universe. But 
such illustrations as these, though necessary and useful, 
cannot throw any light on the structure of the uni verse, since 
they illustrate theories already formed, not facts on which 
theories are to be based. What seemed to me most desir- 
able was that charts should be constructed on which the 
results of telescopic observation should be carefully 
mapped down without reference to any preconceived 
opinions, and solely with the intention of interpreting as 
satisfactorily as possible whatever laws of stellar distribu- 
tion may really exist. It appeared to me that mere lists 
of numbers could afford but unsatisfactory evidence on 
such points. 

Even the mind of a Newton might well shudder before 
the stupendous problem of attempting to educe a true 
theory of the stellar universe from a few laws of statistical 
distribution ; while, on the other hand, pictures of the 
star sphere, or of parts of it, if suitably devised, might at 
once suggest true views. It is easy to illustrate the 
difference between the two methods. Suppose we wished 
to form true ideas respecting the actual distribution of 
clouds in the air, on some day when the whole sky was 
flecked with clouds of various form, colour, and shape ; 
but that we had no way of examining the sky except 
through a movable tube which showed only a small part 



The Depths of Space. 265 

of the sky at a view. Now, if the two following methods 
were available for the enquiry (by combining the observa- 
tions made by a great number of persons), is it not mani- 
fest which would be the most instructive ? By one let 
the sky be assumed divided by a series of circles parallel 
to the horizon, and by a series of half-circles square to the 
horizon, and therefore all crossing at the point overhead ; 
and let the enquirer be supplied with lists informing him 
of the number of clouds in these various sections of the 
sky, ' By the other let a picture be painted, in which all 
the features of the sky as ascertained by the different 
observers are combined artistically into a single view. 

I think no one can doubt that while clear ideas would 
be formed from the study of the picture, not all the statis- 
ticians in the world could derive just views from the 
analysis of the lists of numbers. 

I propose in my next chapter to tell the reader some 
of the facts which come into view, when pictures of the star 
depths are constructed on a certain plan devised to make 
them as instructive as possible, and then to indicate a 
scheme which I have devised for continuing and extending 
the enquiry. I think I shall be able to show not only that 
there are reasons for hoping that a true general theory 
of the stellar system may one clay be formed, but that the 
facts which are already known, or may be inferred, are 
full of interest, and exhibit the universe of stars as far 
more wonderful in extent, in variety of structure, and in 
complexity of detail than had hitherto been supposed. 



266 The Expanse of Heaven. 



CHARTING THE STAR DEPTHS. 

In my last chapter I pointed to the necessity of charting 
the heavens, even as they would be seen by means of a 
very powerful telescope, if we really hope to ascertain 
the laws of the sidereal universe. 

But it is manifest that we must not begin by thus com- 
bining in a single picture all that such a telescope would 
reveal. For let it be considered how incomprehensible 
the scene so presented would appear to us. The dome of 
heaven, even as we see it with the naked eye, presents a 
perplexing display. Those suns seem as the sands on the 
sea-shore for multitude; the glorious streams of stars 
called the Milky Way lie in complex clouds before us. 
The problem even thus presented appears to lie beyond 
our powers. What, then, would be the scene when for 
every star we see thousands and tens of thousands would 
be revealed? How should we be perplexed when the 
clouds of the Milky Way, as now seen, appeared only as 
the brightest masses in a perfect sky of star clouds, in 
which every variety of form, of aggregation, and of con- 
stitution should be presented to our view ! 



Chaining the Star Depths. 267 

Even more incomprehensible would be the streams of 
cloudlets which astronomers call nebulce. Yet even there 
the wonders of the scene would not be at an end. For 
by our assumption the powers of the human observer 
would be so enhanced that he would perceive the motions 
of all the millions of stars, one group tending hither, 
another thither, one region instinct with diverse and 
seemingly random motions, another bearing onwards its 
wealth of stars in one compact body, if a system could be 
called compact whose several orbs were seen to be sepa- 
rated from each other by thousands of millions of miles. 
Even our solar system, if viewed under such conditions, 
would present a most perplexing scheme to one not 
already acquainted with the laws pervading it ; but the 
orbs of the stellar universe are a million times more 
numerous, are arranged according to laws infinitely more 
complex, travel with motions infinitely more varied : 
and though we need not doubt that, if we could but 
perceive the real dependence of the various parts upon 
each other, a perfect harmony would be found to pervade 
every portion, yet that harmony can only be manifest to 
Him in whose eyes a thousand years are as one day. 

We must approach the solution of the great problem, 
then — that is, such solution as we are likely to attain to 
— by gradual steps. We must not attempt to survey the 
whole domain of sidereal astronomy at once, but gradually 
open our eyes to its full extent. This expression is not 
simply figurative. The conception of a gradually in- 



268 The Expanse of Heavm. 

creasing telescopic power corresponds to the idea of a 
gradual opening of the eyes. Half closed at first, the 
eyes of our imaginary enquirer are veiled from the over- 
powering glories of the great star-multitude, they reach 
not very far beyond the range of ordinary human vision ; 
but gradually they become better able to endure these 
wonderful glories, and to understand the full significance 
of the scene ; then they are opened to fresh wonders : 
until at length all that the powers of the telescope can 
reveal to man is disclosed to their view. 

In working, then, by the method of charting I began 
(for I may as well note that I have been practically alone 
in this work) by charting the stars that we can see, 
according to a plan by which the laws of distribution 
should be clearly recognised ; for the charts I drew were 
so contrived that equal spaces on the celestial sphere 
should be represented by equal spaces in the chart. It 
quickly became clear that the stars are not scattered at 
all uniformly over the heavens. There are rich and poor 
regions ; and these are so arranged that while the whole of 
the galactic region is exceedingly rich in naked-eye stars, 
two opposite rich regions, one in the northern and the 
other in the southern heavens, are separated from each 
other (except where the Milky Way on opposite sides 
passes from one to the other) by singularly barren regions. 
It appears a noteworthy circumstance that near the 
centre of the great southern rich region are found those 
two wonderful objects called the Magellanic Clouds, vast 



Charting the Star Depths. 269 

globe-shaped conglomerations (scarcely any other word 
seems so suitable) in which are contained not only myriads 
of stars of all orders of magnitude after the seventh, but 
also every kind of star cloudlet. 

This was only a first step ; though I may remark that 
to this particular part of my work alone I was able to 
apply a somewhat novel but very effective method of 
research. It seemed desirable to ascertain how far the 
apparent aggregation of stars in the rich regions I have 
mentioned, and their segregation from other regions, was 
a real phenomenon — in other words, to test the eye's 
power of forming an opinion on this point. I therefore 
made separate copies of the northern and southern charts 
on the smoothest and most uniform paper I could obtain, 
and then cut out the poor and rich parts of the chart 
and weighed them in a very delicate balance. This 
process told me their relative extent better than any way 
of measurement applicable to such strangely shaped 
regions. I found that, as might have been expected, the 
eye had judged quite correctly, and that when compari- 
son was made between the poorer and richer regions, 
the wealth of the star distribution was in some of the 
latter regions fully five times as great as in some of 
the former. 

But already a remarkable and important feature of 

star distribution had come to light. It was manifest that 

• the Milky Way is a region much more richly strewn with 

naked-eye stars than are other parts of the heavens. Now, 



270 The Expanse of Heaven. 

if the glow of light in the star clouds forming the Milky 
Way were simply due to the great extension of the star- 
system towards these directions, it is very plain that the 
milky light would be produced by stars not separately 
discernible to the naked eye, and that whatever bright 
stars were spread on the Milky Way background would 
be quite unconnected with the great star-strewn regions 
producing the milky light. Thus there ought, on this 
supposition, to be no difference in the richness of bright 
stars over the Milky Way and over the rest of the 
heavens. The fact that there is such a difference, and to 
a very marked degree, as we have seen shows beyond all 
possibility of question that at least the extra number of 
bright stars on the Milky Way, if not all the bright stars 
on that region, are actually associated with those other 
stars, separately undiscernible, which produce the milky 
light of the galaxy. But this being the case, it follows 
that those bright and seemingly large stars are really 
very much larger than the other stars of the galaxy, that 
they owe their superior brightness not to relative near- 
ness, but to inherent superiority over the stars surround- 
ing them. 

This result is well worth noticing, for this chief reason, 
that it exhibits to us a new order in the universe. Pre- 
cisely as we have learned to recognise during the present 
century the existence of a class of bodies in our solar 
system — the asteroids — which are quite distinct as an 
order from the planets, forming a zone or band of small 



Charting the Star Depths. 271 

planets, a kind of scheme before not thought of by 
astronomers, so here in the star clouds of the Milky- 
Way, with interspersed superior orbs, we recognise an 
arrangement which hitherto had not been met with in the 
universe. 

But when this result had been discovered, it seemed 
to me that it would be interesting to follow up the dis- 
covery, by searching for evidence as to the distribution 
of the intermediate order of stars — stars not so bright as 
to be visible to the naked eye, but yet considerably brighter 
than the great multitude of stars which Herschel had 
found strewn through the Milky Way when he examined 
it with his most powerful telescopes. Now, it chanced 
that a few years ago the Grerman astronomer Argelander 
had completed the cataloguing and charting of the stars 
seen in the northern heavens with a telescope 2 J inches 
in opening — -just such a telescope, so far as size is 
concerned, as we commonly see in opticians' windows. 
But even such a telescope as this brings into view 
thousands on thousands of stars which the naked eye 
cannot perceive. 

Although Argelander and his assistants swept rapidly 
over- the northern heavens (dividing it into zones), not 
going more than twice over each part, and doubtless on 
hazy or moonlight nights passing over many stars which 
would have been perceived on a dark and clear sky, they 
yet charted no less than 324,198 stars, of which 310,000, 
or thereabouts, belonged to the northern half of the star 



272 The Expanse of Heaven. 

sphere surrounding us. 1 Now, on very dark and clear 
nights we can perceive on the half of the heavens which 
at any moment may be in view about three thousand 
stars. So that Argelander's telescope showed at least one 
hundred times as many stars a,s we can perceive with the 
unaided eye. Conceive the glorious scene which would 
be disclosed if, for every star we see on the darkest and 
clearest winter nights, a hundred stars should suddenly 
leap into view, the stars of our familiar constellations 
growing at the same time correspondingly brighter, inso- 
much that we should recognise the glories of Orion and 
Auriga, the Bears, the Herdsman, and the Lions — in fine, 
all the constellations known to us, but revealed only by 
their superiority over a hundred times as many stars 
shining as brightly as those few thousands which we now 
perceive. 

Argelander's work was presented in a series of forty 
large folio charts ; and it was necessary to combine these 
in a single chart on the same equal-surface method which 
I had used when mapping the six thousand stars seen 
with the naked eye. I made the circle enclosing the pro- 
posed chart twenty inches in diameter, and then divided 
it into ninety-two concentric zones by suitably drawn 
circles, and drew from the centre 360 radiating lines, so 
that the whole surface was divided into more than twenty 

1 They carried their charts two degrees beyond the celestial equator for 
comparison with a corresponding series of southern maps one of these days 
(or some of those southern nights) to be completed. 



Charting the Star Depths. 273 

thousand pencilled spaces, corresponding to the spaces in 
Argelander's charts. Then into these spaces the stars were 
marked in, being copied by eye-draughts from the charts. 
It will be seen, therefore, that the various degrees of rich- 
ness in stellar distribution were accurately represented in 
the resulting chart ; and it needed but an examination of 
the chart to show whether the stars included within the 
range of Argelander's telescope were gathered more richly 
along the Milky Way or not. But in reality no examina- 
tion was required, since so richly were these stars strewn 
on the Milky "Way, that its figure was as it were shaded 
in by the mere aggregation of the dots representing 
stars. 

Here, then, is fresh evidence of the wonderful consti- 
tution of the Milky Way. We see that this complicated 
aggregation of star streams, for such is the true description 
of the galaxy, consists in the main of a multitude of re- 
latively minute stars, amidst which many stars, so large as 
to be visible to the naked eye, are scattered, while also 
stars of intermediate orders are gathered with great rich- 
ness in the same region of space. 

It follows that when Sir W. Herschel was endeavour- 
ing by means of his powerful telescopes to resolve the 
cloudy light of the Milky Way into separate stars, he was 
not really penetrating, as he supposed, to the remotest 
limits of our stellar system, and bringing into view stars 
which were at a relatively enormous distance, but in many 
cases at least was simply scrutinising more and more 



274 The Expanse of Heaven. 

closely certain definite aggregations of stars, of many 
orders of real magnitude, all intermixed together in the 
same region of space. So that we no longer have any 
evidence, certainly not such convincing evidence as Sir 
W, Herschel supposed, that the limits of our star system 
can be reached. We have nothing to show that far away 
beyond the star groups which he so resolved there may not 
lie other groups which his telescope would not even bring 
into view, far less separate into stars, and all forming parts 
of the same system. Our stellar universe, in fact, no 
longer presents the uniform aspect which it had assumed 
as interpreted by Sir W. Herschel, but shows varieties of 
structure and of aggregation corresponding with, but far 
surpassing in degree, those which we recognise in the solar 
system. 

Here for the present I pause, though I might readily 
dwell on processes of research by which the star-charting 
I have commenced may be extended to far greater depths, 
and the whole heavens surveyed with telescopic powers 
gradually increasing from the small telescope used by 
Argelander to the largest telescopes yet made by man. 
When that has been done, and the results have been duly 
studied, we shall begin to form clearer and worthier ideas 
than hitherto of that amazing scheme of bodies of which 
our sun is a member. We shall find in that system an 
infinite variety of structure. As I have written elsewhere, 
' besides the single suns, the universe contains groups and 
systems and streams of primary suns ; there are galaxies 



Charting the Star Depths. 275 

of minor orbs ; there are clustering stellar aggregations 
showing every variety of richness, of figure, and of dis- 
tribution ; there are all the various forms of star cloudlets, 
resolvable and irresolvable, circular, elliptical, and spiral ; 
and, lastly, there are irregular masses of luminous gas, 
clinging in fantastic convolutions around stars and star 
systems. Nor is it unsafe to assert that other forms 
and varieties of structure will yet be discovered, or that 
hundreds more exist which we may never hope to recog- 



276 The Expanse of Heaven. 



THE STAR DEPTHS ASTIR WITH LIFE. 

I do not know which thought is more stupendous, that 
the millions of suns which people space should all be 
fixed or should all be in exceedingly swift motion. It 
is an impressive conception that multitudes of suns, each 
competent to rule over a scheme of circling worlds, should 
remain steadfast each in its own domain, that the infinite 
universe should be divided, as it were, into separate 
kingdoms, ruled over in the main by single orbs, but 
some governed by multiple suns, and each, undisturbed 
in its integrity by rival empires, constant and stable for 
all time. But it is a no less impressive thought that 
each of these great ruling orbs should be urging its way 
through space with a velocity compared with which the 
swiftest motions known to us are as absolute rest — that 
the mighty star kingdoms of the universe should have 
constantly changing boundaries, or rather, since every 
subordinate orb in every star kingdom must partake in 
the motion of its ruler, that these kingdoms are carried 
bodily onwards, in every second of time passing over 
many miles of their wonderful flight through space. 

But more impressive than either thought is the con- 



The Star Depths Astir with Life. 277 

sideration that to our apprehensions both these conceptions 
are true. Each sun of our universe of suns is indeed in 
swift motion, as is our own. Each bears its family of 
dependent worlds along with it at an amazing velocity. 
Each star domain is continually changing not in boundary 
alone, but altogether. And yet so enormous is the scale 
on which the universe of stars is constructed that while 
momentarily changing it may be regarded as more un- 
changing than any object within its own infinite extent. 
If there could be constructed on any scale which would 
not be too large to prevent the whole being seen at once 
a perfect model of the stellar system, or rather of the 
part of the stellar system which lies within man's cog- 
nisance, and if within that model motions took place 
corresponding to those which are actually taking place 
in the stellar universe, then ages must elapse before the 
appearance of the system would be appreciably altered. 

The most seemingly unchanging objects — a block of 
granite, a mass of steel, a diamond — are in reality under- 
going moment by moment changes of structure, shape, 
and condition which surpass infinitely in extent those 
which would represent the changes in the stellar universe, 
even though the imagined model of that universe were 
as large as some great metropolis. If, passing beyond 
such puny and inadequate conceptions, the distance 
separating our sun from his nearest neighbour among 
the stars were represented by a mile — in which case the 
model would probably have to be as large as our earth — 



2 78 The Expanse of Heaven. 

and supposing that nearest star moving with respect to 
our sun (regarded as at rest) at the rate of 100 miles 
per second, then the motion of the star in the enormous 
model would be so slow that in an hour it would amount 
but to the 850th part of an inch, and it would require 
thirty-five days to traverse a single inch relatively to our 
sun as represented in the same model. It will be con- 
ceived, therefore, how absolutely unchanging a model on 
any ordinary scale would appear. For probably no star 
moves with respect to any other at the rate of 100 miles 
per second ; and a model of the star universe, so far as 
our telescopes reveal it, would require to be several 
miles across, in order that the distance separating our 
sun from the nearest star should be represented by a 
single yard. 

In the star universe, then, we have a strange combina- 
tion of the changing and the unchanging. It is astir 
with energy, instinct with the most amazing vitality, and 
yet it is to our feeble senses constant. Only in the eyes 
of Him to whom a thousand years are as one day, and 
one day as a thousand years, is the life of the universe 
a reality. He alone recognises harmony and perfection 
in the system of star motions. We cannot see the har 
monious relations of the universe regarded as a whole, 
simply because we do not recognise the laws of stellar 
motions. We see stars gathered together in one place 
and sparsely strewn elsewhere, apparently without law 
or order — precisely as an observer of our solar system 



The Star Depths Astir with Life. 279 

from some distant stand-point would see no signs of regu- 
larity in the momentary distribution of the planets. 

But precisely as the astronomer knows that, regarded 
not alone in all its parts, but with due reference to all its 
motions, the solar system is a regular and orderly scheme, 
so to the All-knowing Creator the stellar universe, in- 
harmonious in all its parts if regarded without reference 
to the motions actuating its various members, is a scene 
of regularity and system, because not only are the actual 
places of the stars known to Him (which is not the case 
with astronomers), but the complete series of motions 
which are taking place within the system is recognised 
and understood. 

Let us, however, consider how astronomers first 
ascertained that the stars are not absolutely fixed, and 
what has since been ascertained respecting the stellar 
motions. 

The actual recognition of the displacement of a star 
by its own motion is a work which can only be accom- 
plished by means of a powerful telescope, well mounted, 
and so arranged as to afford the means of determining 
any star's place with extreme nicety. In fact, this amounts 
to saying that the motion of the star must be very much 
magnified before it can be perceived. 

But although this is true of any given astronomer, no 
star moving fast enough to be appreciably displaced to 
ordinary vision in any man's lifetime, yet in the course of 
centuries a star may shift so much in position as no longer 



280 The Expanse of Heaven. 

to occupy the same relative position with respect to other 
stars. And the first recognition of star motion was, in 
point of fact, effected without telescopic assistance. In 
this way : The ancient astronomers noted the passage of 
the moon over certain stars, recording the date and hour 
of the occurrence, and the part of the moon at which 
the star disappeared and re-appeared. Now, the moon's 
motions have been very accurately determined, insomuch 
that astronomers can trace back her steps and learn 
certainly that she was at such and such a distant past 
epoch at such and such a part of the heavens. 

Supposing any star whose concealment by the moon 
has been recorded by ancient astronomers to have re- 
mained in the same place during the interval which has 
since elapsed, the moon's motion traced back to the date 
of the event would carry her over the present place of that 
star. But if at that epoch the star had a different position, 
it is to that ancient position of the star, not to its present 
position, that the calculation would carry back the moon ; 
and if one judged from the present position of the star, 
one would infer that there had either been no conceal- 
ment of the star, or that the circumstances of the con- 
cealment were different from those actually recorded. 

It was thus that astronomers first discovered that 
some at least among the stars are slowly changing their 
place in the heavens. We owe the discovery to Halley, 
the friend and contemporary of Sir Isaac Newton. So 
soon, however, as the fact was recognised in this com- 



The Star Depths Astir with Life. 281 

paratively rough though effective manner, astronomers 
perceived that by carefully determining the places of the 
stars with the telescope they could detect star motions 
much more satisfactorily. This would not be the place 
to describe the methods in use among astronomers to 
determine with great exactness the place of any star. It 
must suffice to note that in these methods the astronomer 
takes advantage of all the refinements of mechanical 
ingenuity, and that the magnifying power of the telescope 
in reality acts to magnify any effects of star motion. So 
that if a magnifying power of 100 is used, the astronomer 
could detect in one year any motion which, to the naked 
eye, would only be discernible in one hundred years. 

Very few motions are discernible to ordinary vision 
(aided, of course, by an instrumental index devised to 
determine a star's place) in so short a time as one 
hundred years. But notice that in twenty or thirty years 
a telescopist, using the very moderate power named, 
would be able to detect a motion which ordinary vision 
would be able to recognise after the lapse of two thousand 
or three thousand years. And our astronomers are not 
limited to twenty or thirty years. They can compare 
their observations with those made by such observers as 
Bradley and his contemporaries nearly a century and a half 
ago. This amounts, with moderate telescopic power, to 
the observation of effects equivalent to those which would 
be presented to the naked eye in the course of more than 
ten thousand years. It will not be wondered at, then, 



282 The Expanse of Heaven. 



,4-™. 



that effects of change should be recognised by astro- 
nomers, possessed as they are of this power of in effect 
extending time by magnifying its operation. 

It may be mentioned that so far as observation has 
extended very few stars in the heavens have unchanging 
apparent positions. It is highly probable that in reality 
every star is in motion. But of course the motions of 
some stars among the thousands dealt with in astronomical 
observations are directed almost exactly towards or from 
the earth, and therefore cannot be recognised by any 
displacement of the star. 

The determination of the actual rate of any star's 
thwart motion is impossible unless the star's distance be 
in the first instance determined ; and, as I have said in a 
former chapter, we know very little about star distances. 
If we take the case of Sirius, whose distance has been set 
at about a million times the distance of the sun, we find 
that the annual thwart motion of this star is such as to 
indicate a real rate of thwart motion of about twelve 
miles per second. 

But it might seem that we are after all in a very 
unfavourable position to form anything like complete or 
satisfactory ideas respecting stellar motions, since we can 
only recognise the thwart motions, and cannot estimate 
even these as actual rates of motion at so many miles per 
second. It has lately chanced, however, that a method 
of spectroscopic observation has enabled astronomers to 
recognise, and even to measure in miles per second, the 



The Star Depths Astir with Life. 283 

motions of stars directly from or towards us. The 
principle of the new method may be thus briefly indicated : 
The spectrum of a star is a rainbow-tinted streak, crossed 
by certain dark lines. If a dark line can be recognised 
as due to any particular vapour, as hydrogen, magnesium, 
or so on, then we know that its place corresponds exactly 
to some particular part of the spectrum's length — some 
particular tint of the red, or orange, or yellow, or green, 
or blue, or indigo, or violet. But tint in light corresponds 
to tone in sound. In one case the number of light waves 
reaching the eye, in the other the number of sound waves 
reaching the ear, in a given time occasions the peculiar 
quality which we call colour in one case, or tone in the 
other. 

Now, the longer light waves make the red, orange, and 
yellow colours, while the shorter make the green, blue, 
indigo, and violet. Again, the longer sound waves make 
the grave tones, and the shorter make the acute tones. 
And we know that motion affects the tone of any sound. 
If the whistle of a railway engine is sounding while the 
engine is passing, it will be noticed that as the engine 
approaches the observer, the tone is acuter than as the 
engine is receding from him, there being a sudden 
lowering of the tone as the engine passes. 

The reason is readily perceived. For when the train 

is approaching more sound waves reach the observer in a 

given time, since the approach of the train is continually 

bringing nearer to him the point whence the sound waves 
13 



284 The Expanse of Heaven. 

come, and so shortening their journey towards him and of 
course the time in which they reach him, the reverse 
taking place when the train is receding. So that the 
ear, which knows nothing of the train's motions, simply 
conveys to the brain at one time the intelligence of waves 
arriving at a certain greater rate, Trading to the sensation 
of an acuter tone, and afterwards the intelligence of waves 
arriving at a lesser rate, leading to the sensation of a 
graver tone. 

Applying this to an approaching or receding star, we 
see that if only the rate of approach or recession bears an 
appreciable proportion to the velocity with which light 
travels (182,000 miles per second), any given colour of 
the star's light will be changed to a colour nearer the 
violet end of the spectrum, while the change will be 
towards the red end of the spectrum if the star is 
receding. This would not affect the colour of the star as 
a whole, but any dark line in the star's spectrum being 
shifted in this way would no longer agree in position with 
the corresponding line of the same element — hydrogen, 
magnesium, or the like — in the spectrum obtained by the 
chemist from that element in his laboratory. If the two 
spectra — that of the element at rest, and that of the star 
carrying that element along with it at an enormous rate 
— can only be compared, we can recognise and even 
measure the star's motion of recession or of approach. 

In this way Dr. Huggins discovered two or three 
years ago that the star Sirius is travelling from us at the 



The Star Depths Astir with Life. 285 

rate of more than twenty miles per second. Since he 
made this discovery a telescope better suited for the work 
has been placed in his hands by the Eoyal Society, and 
with this he has recognised motions of recession or ap- 
proach in the other bright stars, some of these motions 
taking place at the rate of more than fifty miles per 
second. 

In another chapter I shall describe certain peculiarities 
which characterise the stellar motions, and in particular 
(1) the evidence which the star motions afford as to the 
motion of our own ' bright particular star, 9 the sun, with 
his scheme of dependent worlds, and (2) the evidence of 
certain drifting motions among particular star groups. 



286 The Expanse of Heaven. 



THE DRIFTING STARS. 

In former chapters I have compared man to the May-fly, 
and his conceptions of the universe, or what he calls tho 
universe, to the ideas which a reasoning May-fly might 
form of the objects amidst which liis brief career is 
1 passed* And surely there is no subject of research which 
suggests such a comparison more forcibly than the study 
of star movements, A child is hern into the world, grows 

to manhood, becomes, perchance, what we call great, lives 

to the threescore years and ten, or even to those four- 
score years which bring with them weariness of life; and 
during all those years the great universe of stars which 
encompasses us on every hand remains to ordinary percep- 
tions unchanged. Let the heavens be studied on the first 
night after that man was bom, and let them again be 
studied on the first night, after his death, and no change 
in the distribution of the stars shall be perceived. 

And yet during all the 4 years which have elapsed 
every one of those orbs which seem so steadfast lias been 
rushing onwards at a rate 4 compared with which the 
swiftest forms of motion with which we are acquainted — 



The Drifting Stars. 2 8 7 

the speed of the express train, the flight of the bird, even 
the rush of the missiles which we poor ephemera employ 
to destroy our fellow-creatures — areas absolute rest, hi 
every second yon busy star which seems so still has urged 
its way thirty or forty miles upon its wide and as yet 
undetermined career. Not for a moment does it rest, 
even when unseen Ly human eyes ; and yet the career of 
the most long-lived of our race passes while that star 
remains to all ordinary perceptions in an unchanging 
position. 

Yet our short-lived race, puny and feeble though it 
appears compared with the wondrous orbs amidst which 
the earth on which we live exists, has deliberately under- 
taken and not unsuccessfully carried out, the daring 
scheme of determining according to what laws the stars 
move, and in particular (for in reality tin's scheme is the 
most daring of all) of ascertaining from the seeming 
motions of the stars how the sun, that vast orb of which 
our earth is a minute dependent upon whose surface man 
is a most minute moving creature, is moving through 
star-bestrewn space. 

We owe to Sir W. Iferschel the first conception of the 
method "by which the star motions were to be analysed 
for the detection of the motion of our own sun. It is 
clear that if all the stars were at rest, and our sun were 
moving in their midst, then the other stars would appear 
to be affected by motions corresponding to the real 
motions of the sun. If the sun were travelling on a great 



288 The Expanse of Heaven. 

level plain, upon which lay all the other stars, we might 
say that the stars to right and left of him would appear 
to be moving backwards, precisely as the trees, houses, 
and other objects at rest on either side of the track of a 
moving carriage seem to be travelling backwards. But 
as the stars do not lie on a plane surface, but are scattered 
throughout the length and breadth and depth of space, 
we cannot so describe their apparent motions. Neverthe- 
less it is clear that stars on all sides of the sun must 
appear to travel backwards if he is travelling in any 
direction forwards. 

It is common to find it stated that the stars of the 
region towards which the sun is travelling would appear 
to open out, just as the trees of a forest seem to open out 
from each other as the traveller advances towards them ; 
and that the stars of the region which the sun is leaving 
would seem to draw closer together. But no such effect 
could be expected to be recognisable, because the distances 
of the stars are so great. Precisely as when we are 
travelling in a carriage the objects on either side are those 
chiefly affected by apparent motion, so with the stars : 
those on every side of the course of the advancing sun 
would be more affected than those lying in regions towards 
which, or from which, he is moving. 

But a difficulty is introduced in the case of the sun 
which does not appear in the case of some traveller 
moving onwards amidst a number of objects at rest. We 
only infer that the sun is moving because we have seen 



The Drifting Stars. 289 

that the stars are moving. And we cannot for a moment 
suppose that all the star motions are merely apparent, 
and due in reality to the sun's motion. For why should 
the sun, which is only one among many hundreds of thou- 
sands of suns, be the only one which is moving ? Apart 
from this, the motions of the stars are altogether too 
diverse in character to be ascribed to any such simple 
cause as the motion of the sun alone, even if that were 
in itself a reasonable or likely supposition. So that the 
astronomer who wishes to learn in what direction the sun 
is moving has not the same sort of evidence to guide him 
which is afforded to one travelling amidst a number of 
objects at rest. The sun is surrounded by a multitude of 
moving objects, and, to make the determination of his 
motion infinitely more difficult, those objects lie at un- 
known distances, are moving in unknown directions, and 
have unknown velocities. 

Very wonderful is it, therefore, that Sir W. Herschel 
first, and afterwards several other astronomers have, by 
the careful study of the stars' movements, ascertained, 
with what amounts practically to absolute certainty, that 
our sun, with his whole family of planets, is moving 
towards the part of the heavens occupied by the constella- 
tion Hercules. Every investigation of the evidence has 
led to the same general result in this respect. But as to 
the rate of the sun's motion, which is not uncommonly 
presented as though it rested on the same footing, the 
evidence is very much less convincing. It has been said 



290 The Expanse of Heaven. 

that the sun is travelling at the rate of three or four miles 
in every second of time. But when one examines the 
evidence one finds that this conclusion depends on 
assumptions as to the average real magnitude of the stars 
of various orders of apparent brightness. I was long 
since led to conclude that such assumptions were unsafe, 
and also to infer from certain evidence which I had 
collected that our sun moves much more swiftly than had 
been supposed. In fact, speaking generally, I may say 
that I had been led to the opinion that our sun is by no 
means so important a member of the star system as the 
majority of the leading brilliants of the heavens, and that 
consequently the real distances of those brilliants are 
greater than would be inferred from the supposition that 
they are the sun's equals only. Hence it follows, of 
course, that the signs of motion among these stars indicate 
much greater real motions with respect to the sun. This 
amounts to saying that not only the motions which those 
stars have within the star system, but those also which 
are only relative, and produced by the sun's real motion, 
are much greater than had been inferred. So that the 
sun's real motion to which these relative motions are 
solely due must (if my view were correct) be much greater 
than was supposed. 

I think this view of mine has been confirmed by the 
evidence obtained to show that the sun belongs to an order 
of stars inferior to that including Sirius, Vega, and some 
three hundred stars studied spectroscopically by the Italian 



The Drifting Stars. 291 

astronomer Secchi. Then the results of Huggins's labours, 
indicating motions of recession and approach by thirty, 
forty, and even fifty miles per second, render it extremely 
unlikely that our sun's whole motion amounts but to three 
or four miles per second. 

I have said that as to the sun's motion towards Hercules 
little doubt can be entertained, because every investigation 
of the subject has led to the same result. But it is worthy 
of notice that the last and in some respects the most 
complete investigation of the matter, by my friend Mr. 
Dunkin, working under the general directions of the 
Astronomer Eoyal, while pointing to the same general 
result, showed also the effects of that difficulty to which 
I have referred above — the multiplicity of real motions 
among the stars. For after the calculation was finished 
which showed that the sun's motion towards Hercules 
accounts for a greater proportion of the observed move- 
ments than any other assumption, Mr. Dunkin proceeded 
to enquire what proportion of the observed movements 
was actually accounted for in this way. The result was 
to show that only about one-thirtieth part of the observed 
motions could be regarded (on the assumptions adopted) 
as due to the sun's motion. 

Sir J. Herschel remarked on this, ' No one need be 
surprised. If the sun move in space, why not also the 
stars ? And if so, it would be manifestly absurd to expect 
that any movement could be assigned to the sun, by any 
system of calculation, which would account for more than 



292 The Expanse of Heaven. 

a very small portion of the observed displacements. 1 But 
what is indeed astonishing in the whole affair is, that 
among all this chaotic heap of miscellaneous movement, 
among all this drift of cosmical atoms, of the laws of 
whose motions we know absolutely nothing, it should be 
possible to place the finger upon one small portion of the 
sum total, to all appearance undistinguishably mixed up 
with the rest, and to declare with full assurance that this 
particular portion of the whole is due to the motion of 
our own solar system.' 

When we add to this thought the consideration to 
which I have already adverted — viz. that the movements 
themselves are such that their effects in the course of 
the longest life are utterly undiscernible — the wonder is 
enhanced that men should venture to attack a problem 
so recondite, and that their daring should have been 
rewarded with success. 

The thought has even been conceived that possibly 
something might be learned, not only as to the direction 
and velocity with which the sun is moving, but as to the 
shape of the path which he will describe in some enormous 
period compared with which the thousands of years which 
are included in what we call history, the millions whose 

1 In an Appendix to my * Essays on Astronomy ' I have indicated 
reasons for expecting, however, that one-half of the observed displacements 
would be accounted for by the sun's motions. This is mathematically de- 
monstrable, and is in fact so demonstrated in the work mentioned. It fol- 
lows that the smallness of the actual correction results from errors in the 
assumptions on which the calculation has been effected, a result according 
well with my inferences from other considerations. 



The Drifting Stars. 293 

passage is indicated by the condition of the earth's crust — 
nay, even the thousands of millions inferred from the 
condition of the solar system — are but as a single moment. 

It was once thought that the German astronomer 
Madler had found the true centre around which all the 
stars of the galaxy, including our own sun, are revolv- 
ing in the star Alcyone, the leading brilliant of the 
Pleiades, But it is now generally acknowledged that the 
evidence on which Madler based this view was quite in- 
sufficient* 

Probably science will have to wait hundreds of years 
before any just ideas can be formed as to the general laws 
according to which the stars of the galaxy are moving. 

In the meantime, however, it appears desirable and 
useful to search for subordinate laws of motion. The 
idea occurred to me three or four years ago that if the 
motions of the stars could be mapped, instead of being 
merely tabulated as hitherto, signs would be traced of 
such subordinate laws. In particular it seemed to me 
not unlikely that a community of motion would be 
recognised among stars really forming subordinate star 
families. 

The method I used for charting star motions was as 
follows : — I drew charts, including all the stars whose 
thwart motions have been recognised, and to each star I 
attached a small arrow showing the direction in which 
the star is moving. Moreover, I made the length of the 
arrow proportionate to the rate of the star's thwart motion 



294 The Expanse of Heaven. 

on the heavens. Each arrow was made just so long that 
while one end indicated the present place of the star the 
other end or point indicated the place which the star will 
have thirty-six thousand years hence. It will give an 
idea of the extreme slowness of the apparent motions to 
mention that notwithstanding the enormous number of 
years to which each arrow-length corresponded the greater 
number of arrows were very short. 

I have said that my object was to determine whether 
any set stars show a tendency to drift together. I recog- 
nised several instances where, as it seemed to me, this 
tendency to star-drift was strongly marked. One of these 
I selected as the subject for a scientific prediction. The 
stars affected by star-drift were five of the seven forming 
the familiar Plough (or Charles's Wain), and the pecu- 
liarity of the case was this, that all five were drifting 
nearly in the same direction as regarded their apparent 
thwart motions, and nearly at the same rate, this motion 
taking place in a direction nearly opposite to that due to 
the sun's motion in space. 

I knew that Dr. Huggins would soon be able to apply 
to the leading stars of our northern heavens that spectro- 
scopic method of determining motions of recession and 
approach which I sketched in the last chapter. Now, if 
the five stars in the Plough are really drifting in space, 
it would follow that they have a common motion of re- 
cession or approach, whereas if the drift were apparent 
only, there would be no such community of motion in 



The Drifting Stars. 295 

the line of sight. To indicate, therefore, the confidence 
which I had in the reasoning which had led me to the 
opinion that those five stars really are drifting together 
through space, as a single system, I predicted that when- 
ever Dr. Huggins should apply to them the new spectro- 
scopic method he would find that they were either all 
approaching or all receding, and at a common rate. 

This prediction was exactly confirmed by the event 
two years later. It happened that Dr. Huggins had 
forgotten which of the seven stars form the drifting set 
of five, supposing the ' two pointers ' or hind wheels of 
the Plough, the other two or front wheel-stars, and the 
first horse to be the five, whereas the five are the farthest 
pointer from the pole, the front wheel-stars, and the 
stars representing the two horses next to the wain. The 
observation of the pointer nearest to the pole showed that 
that star is approaching, and the observation of the 
pointer farthest from the pole showed that that star is 
receding at the rate of nearly twenty miles per hour. So 
Dr. Huggins judged that I was mistaken, at any rate as 
respected those two stars, which were seen to be travelling 
in different directions. He proceeded, however, with his 
observations. He found both the remaining wheel-stars 
receding at the rate of about twenty miles per second. 
The star representing the first horse was found to be 
receding at the same rate, and lastly the star representing 
the second horse. Here, then, were five stars receding 
at the rate of about twenty miles per second ; but Dr. 



296 The Expanse of Heaven. 

Huggins supposed at the moment that these were not the 
five stars respecting which I had made my little pre- 
diction. On turning, however, to my * Other Worlds ' 
(published two years before his observations were made), 
he found that it was the set of five stars which he had 
found to be thus receding at a common rate which I had 
described as, in my belief, forming a drifting set. 

I think the inference is fair that my general theory 
respecting local star-drifts is correct, and that among 
those stars which form our familiar systems there are 
groups travelling as systems through space. A strange 
thought truly, when we remember its consequences. It 
shows that, notwithstanding the enormous distances which 
separate these stars from each other, yet vaster distances, 
or rather distances of a higher order of vastness, separate 
that system of stars from the surrounding parts of the 
galaxy. It presents to us, also, the wonderful thought 
that cycles of revolution must exist within that system, 
compared with which the longest periods of motion re- 
cognised within our solar system must be regarded as 
absolutely insignificant. We are shown in such star 
systems an order of created things unlike any that before 
we had known. One other form of evidence has been 
given to show the infinite variety which pervades every 
part of the universe. 



THE MILKY WAY. 

Lo ! these are but a portion of His ways ; they utter but a whisper of 
His glory. — Job xxvi. 14. 

If on a calm, clear night, when there is no moon, we 
regard the star-lit sky, we see spanning the vast concave 
of the heavens a zone of cloudy light. In our country, 
where the air is seldom free from haze and vapour, even 
when it appears clearest, this wonderful zone is faint and 
indistinct. Only in certain portions can we recognise its 
lustre so distinctly as to feel assured (unless acquainted 
with its figure and position) that we are not looking at 
clouds high up in the air. But in southern latitudes 
the Milky Way is aglow with light. There it is seen as 
a brilliant band athwart the heavens — 

A broad and ample road, whose dust is gold, 
And pavement stars, as stars to us appear. 

We cannot wonder that the ancient astronomers should 
have looked with wonder on this amazing phenomenon. 
Steadfast as the stars amidst which its course is laid, the 
galaxy shone night after night before their eyes, and 
offered a noble problem for their thoughts. Nor did they 



298 The Expanse of Heaven. 

fail to perceive the meaning of that steadfastness which, 
to the unthinking, would have had no significance. They 
saw that the wondrous cloud must lie at an enormous 
distance ; and that in all probability its light must be 
produced by the combined lustre of countless stars, re- 
moved to so great a distance as to be separately indis- 
tinguishable. 

Manilius, their astronomical poet, puts forward this 
stupendous conception, and we find Ovid describing the 
Milky Way in terms not unlike (setting aside their 
Paganism) those in which one acquainted with modern 
astronomical results might poetically present them : — 

A way there is in heaven's extended plain, 
Which when the skies are clear is seen below, 
And mortals by the name of Milky know ; 
The groundwork is of stars, through which the road 
Lies open to the Thunderer's abode. 

But it is when the Milky Way is studied with the 
telescope that the true glories of this wonderful zone are 
seen. A large instrument is not needed. Galileo saw the 
wonders of the galaxy with his small and imperfect Q optic 
tube ' — a telescope which, in our day, though invaluable 
as a relic of the great astronomer, would be worth but a 
few shillings, so far as its optical performance is concerned. 
Wright of Durham analysed the depths of the Milky 
Way, and formed a sound opinion as to the true nature 
of the zone by means of a telescope only ten inches in 
length. The smallest telescope which opticians sell for 



The Milky Way. 299 

star-gazing, when turned upon certain parts of the galaxy, 
will reveal a scene of wonder which is calculated to fill 
the least thoughtful mind with a sense of the infinite 
power and wisdom of the Almighty. Countless stars pass 
into view as the telescope is swayed by the earth's rota- 
tion athwart the rich regions of the galaxy. 

There are stars of all orders of brightness, from those 
which (seen with the telescope) resemble in lustre the 
leading glories of the firmament down to tiny points 
of light only caught by momentary twinklings. Every 
variety of arrangement is seen. Here the stars are 
scattered as over the skies at night ; there they cluster in 
groups, as though drawn together by some irresistible 
power; in one region they seem to form sprays of 
stars like diamonds sprinkled over fern leaves ; else- 
where they lie in streams and rows, in coronets and loops 
and festoons resembling the star festoon which, in the 
constellation Perseus, garlands the black robe of night. 
Nor are varieties of colour wanting to render the dis- 
play more wonderful and more beautiful. Many of 
the stars which crowd upon the view are red, orange, 
and yellow. Aflaong them are groups of two and three 
and four (multiple stars, as they are called) amongst 
which blue, and green, and lilac, and purple stars appear, 
forming the most charming contrast to the ruddy and 
yellow orbs near which they are commonly seen. 

But it is when we consider what it is that we are 
really contemplating that the true meaning of the scene 



300 The Expanse of Heaven. 

is discerned, that the true lesson taught by the star depths 
is understood. Then we may say with the poet, but in 
another sense — 

The floor of heaven 
Is thick inlaid with patines of bright gold ; 
There's not the smallest orb which thou behold'st, 
But in his motion like an angel sings, 
Still quiring to the young-eyed cherubim. 

The least of the stars seen in the galactic depths — even 
though the telescope which reveals it be the mightiest 
yet made by man, so that with all other telescopes that 
star would be unseen — is a sun like our own. It is a 
mighty mass, capable of swaying by its attraction the 
motions of worlds, like our earth and her fellow-planets, 
circling in their stately courses around it. It is an orb 
instinct with life (if one may so speak), aglow with fiery 
energy, pouring out each moment supplies of life and 
power to the worlds which circle around it. It is a mighty 
engine, working out the purpose of its Great Creator ; it 
is a giant heart, whose pulsations are the source whence a 
myriad forms of life derive support : and until the fuel 
which maintains its fires shall be consumed, that mighty 
engine will fulfil its work ; until its life-blood shall be 
exhausted, that giant heart will throb unceasingly. And 
more wonderful yet perhaps is the thought that where all 
seems peace and repose, there is in reality a clangour and 
a tumult compared with which all the forms of uproar 
known upon earth sink into utter insignificance. 

We know something of the processes at work upon our 



The Milky Way. 301 

own sun. We know of storms raging there, in which fiery- 
vapour masses, tens of thousands of miles in breadth, sweep 
onward at a rate exceeding a hundred-fold in velocity 
the swiftest rush of our express trains. We see matter 
flung forth from the depths beneath the sun's blazing 
surface to a height exceeding ten and twenty-fold the 
diameter of the globe on which we live. And we know 
that these tremendous motions, though they seem to take 
place silently, must in reality be accompanied with a 
tumult and uproar altogether inconceivable. We know 
that precisely as distance so reduces the seeming dimen- 
sions of these vapour masses, and their seeming rate of 
motion, that even in the most powerful telescopes they 
appear like the tiniest of the clouds which fleck the bosom 
of the summer sky, and change as slowly in their seeming 
shape ; so distance partly, and partly the absence of a 
medium to convey the sound, reduces to utter silence a 
noise and clangour compared with which the roar of the 
hurricane, the crash of the thunderbolt, the bellowing of 
the volcano, and the hideous groaning of the earthquake 
are as absolute silence. 

What, then, must be our thoughts when we see 
thousands and thousands of stars, all suns like our own, 
and many probably far surpassing him in splendour, 
passing in stately progress across the telescopic field of 
view ? The mind sinks appalled before the amazing 
meaning of the display. As we gaze at the wondrous 
scene an infinite significance is found in the words of the 



302 The Expanse of Heaven. 

inspired Psalmist : ' When I consider the heavens, the work 
of Thy hands, the sun and stars which Thou hast ordained, 
what is man that Thou art mindful of him ? or the son 
of man that Thou regardest him ? ' 

It has been said that with the telescopes with which 
the Herschels have surveyed the depths of heaven twenty 
millions of stars are visible. But these telescopes do not 
penetrate to the limits of the star system. In certain 
parts of the Milky Way, Sir W. Herschel not only failed 
to penetrate the star-depths with his gauging telescope 
(here spoken of), though the mirror was eighteen inches in 
width ; but even when he brought into action his great 
forty-feet telescope, with its mirror four feet across, he 
still saw that cloudy light which speaks of star depths as 
yet unfathomed. Nay, the giant telescope of Lord Eosse 
has utterly failed to penetrate the ocean of space which 
surrounds us on all sides. 

And even this is not all. These efforts to resolve the 
galaxy into its component stars have been applied to por- 
tions of the Milky Way which (there is now reason to 
believe) are relatively near to us. But in the survey of 
the heavens with powerful telescopes streams of cloudy 
light have been seen, so faint as to convey the idea of 
infinite distance, and no telescope yet made by man has 
shown the separate stars which doubtless constitute these 
almost evanescent star-regions. We are thus brought into 
the presence of star clouds as mysterious to ourselves as 
the star clouds of the galaxy were to the astronomers of 



The Milky Way. 303 

old times. After penetrating, by means of the telescope, 
to depths exceeding millions of times the distance of the 
sun (inconceivable though that distance is), we find our- 
selves still surrounded by the same mysteries as when we 
first started. Around us and before us there are still the 
infinite star depths, and the only certain lesson we can be 
said to have learned is, that those depths are and must ever 
remain unfathomable. Truly, the German poet Eichter 
has spoken well in those wonderful words which our own 
prose poet De Quincey has so nobly translated; his 
splendid vision aptly expresses the feebleness of man's 
conceptions in the presence of the infinite wonders of 
creation : — 

4 Grod called up from dreams a man into the vestibule 
of heaven, saying, u Come thou thither, and see the glory 
of My house." And to the angels which stood around His 
throne He said, " Take him, strip from him his robes of 
flesh ; cleanse his vision, and put a new breath into his 
nostrils, only touch not with any change his human heart, 
the heart that weeps and trembles." It was done ; and 
with a mighty angel for his guide the man stood ready 
for his infinite voyage ; and from the terraces of heaven, 
without sound or farewell, at once they wheeled away into 
endless space. Sometimes with the solemn flight of angel 
wings they passed through Zaharas of darkness, through 
wildernesses of death, that divided the worlds of life; 
sometimes they swept over frontiers that were quickening 
under prophetic motions from Grod. Then from a distance 



304 The Expanse of Heaven. 

which is counted only in heaven, light dawned for a time 
through a shapeless film ; by unutterable pace the light 
swept to them, they by unutterable pace to the light. In 
a moment the rushing of planets was upon them ; in a 
moment the blazing of suns was around them. 

4 Then came eternities of twilight, that revealed but 
were not revealed. On the right hand and on the left 
towered mighty constellations, that by self-repetitions 
and answers from afar, that by counter-positions, built 
up triumphal gates, whose architraves, whose archways, 
horizontal, upright, rested, rose, at altitude, by spans that 
seemed ghostly from infinitude. Without measure were 
the architraves, past number were the archways, beyond 
memory the gates. Within were stairs that scaled the 
eternities around ; above was below and below was above, 
to the man stripped of gravitating body ; depth was 
swallowed up in height insurmountable, height was 
swallowed up in depth unfathomable. Suddenly, as thus 
they rode from infinite to infinite, suddenly, as thus 
they tilted over abysmal worlds, a mighty cry arose that 
systems more mysterious, that worlds more billowy, other 
heights and other depths, were coming, were nearing, 
were at hand. 

'Then the man sighed and stopped, shuddered and 
wept. His overladen heart uttered itself in tears, and he 
said, " Angel, I will go no farther ; for the spirit of man 
acheth with this infinity. Insufferable is the glory of 
God. Let me lie down in the grave, and hide me from 



The Milky Way. 305 

the persecution of the Infinite, for end I see there is 
none." And from all the listening stars that shone around 
issued a choral voice, "The man speaketh truly: end 
there is none that ever yet we heard of! " 6< End is there 
none ? " the angel solemnly demanded ; " is there indeed 
no end ? And is this the sorrow that fills you? " But no 
voice answered, that he might answer himself. Then the 
angel threw up his glorious hands to the heaven of 
heavens, saying, " End is there none to the universe of 
God. Lo ! also, there is no beginning." ' 



LIST OF A UTHORS AND SUBJECTS OF THEIR BOOKS, 



TO BE PUBLISHED IN THE 



International Scientific Series. 



Rev. M. J. Berkeley, M. A., F. L. S., 
and M. Cooke, M. A., LL. D., Fungi; 
their Nature, Influences, and Uses. 

Prof. Oscar Schmidt (University of Stras- 
burg), The Theory of Descent and 
Darwinism. 

Prof. Vogel (Polytechnic Academy of Ber- 
lin), The Chemical Effects of Light. 

Prof. W. Kingdom Clifford, M. A., 
The First Principles of the Exact Sci- 
ences explained to the Non-mathemati- 
cal. 

Prof. T. H. Huxley, LL. D., F. R. S., 
Bodily Motion and Consciousness. 

Dr. W. B. Carpenter, LL. D., F. R. S., 
The Physical Geography of the Sea. 

Prof. William Odling, F. R. S., The Old 
Chemistry from the New Stand-point 

Prof. Sheldon Amos, The Science of Law. 

W. Lauder Lindsay, M.D., F. R. S. E., 

Mind in the Lower A nimals. 

Sir John Lubbock, Bart., F. R. S., The 
A ntiquity of Man. 

Prof. W. T. Thiselton Dyer, B. A., 
B. S. C, Form and Habit in Flower- 
ing Plants. 

Prof. Michael Foster, M. D., Proto- 
plasm and the Cell Theory. 

Prof. W. Stanley Jevons, The Logic of 
Statistics. 

Dr. H. Charlton Bastian, M.D.,F.R.S., 
The Brain as an Organ of Mind. 

Prof. A. C. Ramsay, LL. D., F R S 
Earth Sculpture; Hills, Valleys, 
Mountains, Plains, Rivers, Lakes; 
how they were Produced, and how 
they have been Destroyed. 

Prof: Rudolph Virchow (University of 
Berlin), Morbid Physiological Action. 

Prof. Claude Bernard (College of 
France), Physical and Metaphysical 
Phenomena of Life. 

Prof. A. Quetelet (Brussels Academy of 
Sciences), Social Physics. 



Prof. H. Sainte-Claire Deville, A n In- 
troduction to General Chemistry. 

Prof. Wurtz, Atoms and the Atomic 
Theory. 

Prof. De Quatrefages, The Negro 
Races. 

Prof. Lacaze-Duthiers, Zoology since 

Cuvier. 
Prof. Berthelot, Chemical Synthesis. 

Prof. J. Rosenthal, General Physiology 

of Muscles and Nerves. 
Prof. C A. Young (Dartmouth College), 

The Sun. 

Prof. James D. Dana, M. A., LL. D., On 

Cephalization ; or^ Head- Characters 
in the Gradation and Progress of 
Life. 

Prof. S. W. Johnson, M. A., On the Nu- 
trition of Plants. 

Prof. Austin Flint, Jr., M. D., The Ner- 
vous System and its Relation to the 
Bodily Functions. 

Prof. W. D. Whitney, Modern Linguis- 
tic Science. 

Prof. Bernstein (University of Halle), 
Physiology of the Senses. 

Prof. Ferdinand Cohn (University of 
Breslau), Thallotyphes {Algae Lichens 
Fungi). 

Prof. Hermann (University of Zurich), 
Respiration. 

Prof. Leuckart (University of Leipsic), 
Outlines of A nimal Organization. 

Prof. Liebreich (University of Berlin), 

Outlines of Toxicology. 
Prof. Kundt (University of Strasburg), 

On Sound. 
Prof. Lonmel (University of Erlangen), 

Optics. 
Prof. Rees (University of Erlangen), On 

Parasitic Plants. 
Prof. Steinthal (University of Berlin), 

Outlines of the Science of Language. 



D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



Opinions of the Press on the "International Scientific Series." 



Tyndall's Forms of Water. 

I vol., i2mo. Cloth. Illustrated ; Price, $1.50. 

" In the volume now published, Professor Tyndall has presented a noble illustration 
of the acuteness and subtlety of his intellectual powers, the scope and insight of his 
scientific vision, his singular command of the appropriate language of exposition, and 
the peculiar vivacity and grace with which he unfolds the results of intricate scientific 
research." — N. Y. Tribune. 

" The ■ Forms of Water/ by Professor Tyndall, is an interesting and instructive 
little volume, admirably printed and illustrated. Prepared expressly for this series, it 
is in some measure a guarantee of the excellence of the volumes that will follow, and an 
indication that the publishers will spare no pains to include in the series the freshest in- 
vestigations of the best scientific minds." — Boston yournal. 

" This series is admirably commenced by this little volume from the pen of Prof. 
Tyndall. A perfect master of his subject, he presents in a style easy and attractive his 
methods of investigation, and the results obtained, and gives to the reader a clear con- 
ception of all the wondrous transformations to which water is subjected." — Churchman. 



II. 

Bagehot's Physics and Politics. 

1 vol., i2mo. Price, $1.50. 

" If the * International Scientific Series 1 proceeds as it has begun, it will more than 
fulfil the promise given to the reading public in its prospectus. The first volume, by 
Professor Tyndall, was a model of lucid and attractive scientific exposition ; and now 
we have a second, by Mr. Walter Bagehot, which is not only very lucid and charming, 
but also original and suggestive in the highest degree. Nowhere since the publication 
of Sir Henry Maine's 'Ancient Law,' have we seen so many fruitful thoughts sug- 
gested in the course of a couple of hundred pages. . . . To do justice to Mr. Bage- 
hot's fertile book, would require a long article. With the best of intentions, we a:e 
conscious of having given but a sorry account of it in these brief paragraphs. But we 
hope we have said enough to commend it to the attention of the thoughtful leader." — 
Prof. John Fiske, in the Atlantic Monthly. 

"Mr. Bagehot's style is clear and vigorous. We refrain from giving a fuller ac- 
count of these suggestive essays, only because we are sure that our readers will find it 
worth their while to peruse the book for themselves ; and we sincerely hope that the 
forthcoming parts of the 'International Scientific Series' will be as interesting." — 
A the?ieeum. 

" Mr. Bagehot discusses an immense variety of topics connected with the progress 
of societies and nations, and the development of their distinctive peculiarities; and his 
book shows an abundance of ingenious and original thought." — Alfred Russeh 
Wallace, in Nature. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



Opinions of the Press o?i the " International Scientific Series" 



ill. 



Foods. 



By Dr. EDWARD SMITH. 
I vol., i2mo. Cloth. Illustrated Price, $1.75. 

In making up The International Scientific Series, Dr. Edward Smith was se- 
lected as the ablest man in England to treat the important subject of Foods. His services 
were secured for the undertaking, and the little treatise he has produced shows that the 
choice of a writer on this subject was most fortunate, as the book is unquestionably the 
clearest and best-digested compend of the Science of Foods that has appeared in our 
language. 

" The book contains a series of diagrams, displaying the effects of sleep and meals 
on pulsation and respiration, and of various kinds of food on respiration, which, as the 
results of Dr. Smith's own experiments, possess a very high value. We have not far 
to go in this work for occasions of favorable criticism ; they occur throughout, but are 
perhaps most apparent in those parts of the subject with which Dr. Smith's name is es- 
pecially linked." — London Examiner, 

" The union of scientific and popular treatment in the composition of this work will 
afford an attraction to many readers who would have been indifferent to purely theoreti- 
cal details. . . . Still his work abounds in information, much of which is of great value, 
and a part of which could not easily be obtained from other sources. Its interest is de- 
cidedly enhanced for students who demand both clearness and exactness of statement, 
by the profusion of well-executed woodcuts, diagrams, and tables, which accompany the. 
volume. . . . The suggestions of the author on the use of tea and coffee, and of the va? 
rious forms of alcohol, although perhaps not strictly of a novel character, are highly in- 
structive, and form an interesting portion of the volume." — N. Y. Tribune. 



IV. 

Body and Mind. 

THE THEORIES OF THEIR RELATION. 

By ALEXANDER BAIN, LL. D. 

1 vol., i2mo. Cloth Price, $1.50. 

Professor Bain is the author of two well-known standard works upon the Science 
of Mind— "The Senses and the Intellect," and "The Emotions and the Will." He is 
one of the highest living authorities in the school which holds that there can be no sound 
or valid psychology unless the mind and the body are studied, as they exist, together. 

" It contains a forcible statement of the connection between mind and body, study- 
ing their subtile interworkings by the light of the most recent physiological investiga- 
tions. The summary in Chapter V., of the investigations of Dr. Lionel Beale of the 
embodiment of the intellectual functions in the cerebral system, will be found the 
freshest and most interesting part of his book. Prof. Bain's own theory of the connec- 
tion between the mental and the bodily part in man is stated by himself to be as follows : 
There is ' one substance, with two sets of properties, two sides, the physical and the 
mental — a double-faced ratify. .' While, in the strongest manner, asserting the union 
of mind with brain, he yet denies 'the association of union in place,' but asserts the 
union of close succession in time,' holding that 'the same being is, by alternate fits, un- 
der extended and under unextended consciousness." ' — Christian Register. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



Opinions of the Press on the "International Scientific Series." 



v. 

The Study of Sociology. 

By HERBERT SPENCER. 

i2mo. Cloth Price, $1.50. 

"The Study of Sociology " was written for the purpose of conveying to the reading 
public more definite ideas concerning the nature, claims, scope, limits, and difficulties, 
of the Science of Sociology. It is intended to prepare the way for the author's great 
work on the " Principles of Sociology," which is to follow the " Principles of Psychol- 
ogy." But, while serving thus as an introduction to the larger work, the present vol- 
ume is complete in itself. Its style is exceedingly clear and vigorous, and the book 
abounds with a wealth of illustration. 

" The philosopher whose distinguished name gives weight and influence to this vol- 
ume, has given in its pages some of the finest specimens of reasoning in all its forms 
and departments. There is a fascination in his array of facts, incidents, and opinions, 
which draws on the reader to ascertain his conclusions. The coolness and calmness of 
his treatment of acknowledged difficulties and grave objections to his theories win for 
him a close attention and sustained effort, on the part of the reader, to comprehend, fol- 
low, grasp, and appropriate his principles. This book, independently of its bearing 
upon sociology, is valuable as lucidly showing what those essential characteristics are 
which entitle any arrangement and connection of facts and deductions to be called a 
science. " — Episcopalian. 

"To those who are already acquainted with Mr. Spencer's writing, there is no need 
of recommending the work ; to those who are not, we would say, that by reading ' The 
Study of Sociology ' they will gain the acquaintance of an author who, for knowledge, 
depth of thought, skill in elucidation, and originality of ideas, stands prominently for- 
ward in the front rank of the glorious army of modern thinkers. 'The Study of Soci- 
ology' is the fifth of 'The International Scientific Series,' and for beauty of type and 
elegant appearance is worthy of the great publishing-house of Messrs. Appleton & Co." 
— Boston Gazette. 

^ "This volume belongs to 'The International Scientific Series,' which was projected 
with so high a standard and which is being so successfully carried out. The value and 
character of the whole may fairly be judged by this and the preceding volumes. The 
principle of the enterprise is that each subject shall be treated by the writer of greatest 
eminence in that department of inquiry, and it is well illustrated in the present work. 
Herbert Spencer is unquestionably the foremost living thinker in the psychological and 
sociological fields, and this volume is an important contribution to the science of which 

it treats It will prove more popular than any of its author's other creations, for 

it is more plainly addressed to the people and has a more practical and less speculative 
cast. It will require thought, but it is well worth thinking about." — Albany Evening 
Journal. 

"Whether the reader agrees with the author or not, he will be delighted with the 
work, not only for the beauty and purity of its style, and breadth and cyclopedic char- 
acter of Mr. Spencer's mind, but also for its freedom from prejudice and kindred imper- 
fections." — Norwich Bulletin. 

"This work compels admiration by the evidence which it gives of immense re- 
search, study, and observation, and is withal written in a popular and very pleasing 
style. It is a fascinating work, as well as one of deep practical thought." — Boston Post. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



Opinions of the Press on the " International Scientific Series" 



VI. 

The New Chemistry. 

By JOSIAH P. COOKE, Jr., 

Erving Professor of Chemistry and Mineralogy in Harvard University. 

I vol., l2mo. Cloth Price, $2.00. 

44 The book of Prof. Cooke is a model of the modern popular science work. It has 
just the due proportion of fact, philosophy, and true romance, to make it a fascinating 
companion, either for the voyage or the study." — Daily Graphic. 

" This admirable monograph, by the distinguished Erving Professor of Chemistry 
in Harvard University, is the first American contribution to 'The International Scien- 
tific Series,' and a more attractive piece of work in the way of popular exposition upon 
a difficult subject has not appeared in a long time. It not only well sustains the char- 
acter of the volumes with which it is associated, but its reproduction in European coun- 
tries will be an honor to American science. It is, moreover, in an eminent degree, 
timely, for, between the abandonment of its old views and the bewilderment caused 
by the new, chemical science was getting into a demoralized condition. A work was 
greatly needed that should relieve the discomfort of transition, and bridge over the 
gulf between the old order of ideas and those which are to succeed them. Professor 
Cooke's compendious contribution to the present exigencies of chemical literature will 
give the students of the science exactly the help they need, and pass them over by an 
easy and pleasant route into the new realm of chemical philosophy." — New York 
Tribune. 

44 AH the chemists in the country will enjoy its perusal, and many will seize upon it 
as a thing longed for. For, to those advanced students who have kept well abreast of 
the chemical tide, it offers a calm philosophy. To those others, youngest of the class, 
who have emerged from the schools since new methods have prevailed, it presents a 
generalization, drawing to its use all the data, the relations of which the newly-fledged 
fact-seeker may but dimly perceive without its aid. ... To the old chemists, Prof. 
Cooke's treatise is like a message from beyond the mountain. They have heard of 
changes in the science; the clash of the battle of old and new theories has stirred them 
from afar. The tidings, too, had come that the old had given way ; and little more than 
this they knew. . . . Prof. Cooke's 4 New Chemistry' must do wide service in bringing 
to close sight the little known and the longed for. . . . As a philosophy it is elemen- 
tary, but, as a book of science, ordinary readers will find it sufficiently advanced." — 
Utica Morning Herald. 

"A book of much higher rank than most publications of its class. It treats only 
of modern chemical theories — relating to molecules, combining proportions, reactions, 
atomic weights, isomerism, and the synthesis of organic compounds — taking one into 
the very arcana of chemical mysteries. Though there are no more recondite branches 
of the science than those here explained and illustrated, such is Professor Cooke's 
clearness that he may be said to make every thing plain to the average reader, who 
will but take pains with his lessons. Professor Cooke reminds us, in his simplicity and 
lucidity of statement, of Professor Tyndall, than which there can be no higher praise." 
— New York Journal of Commerce. 

" The aim of the work is to furnish a hand-book of a symmetrical science, resting 
fundamentally upon the law of Avogadro that * equal volumes of all substances, when 
in the state of gas and under like conditions, contain the same number of molecules.' 
It is to a rigid adherence to this law and the deductions which flow from it that chem- 
istry, as now taught, owes the marked difference which separates it from the chemistry 
taught a few years ago. The original lectures of Professor Cooke, enlarged and 
somewhat modified, present in their present form a clear and full exposition of the sci- 
ence, and will form a useful text-book as well as a volume of unusual interest to the 
lovers of physical science." — New York World. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



Opinions of the Press on the "International Scientific Series" 

VII. 

The Conservation of Energy. 

By BALFOUR STEWART, LL. D„ F. R. S. 

With an Appendix treating of the Vital and Mental Applications of the Doctrine. 

I vol., i2mo. Cloth. Price, $1.50. 

m " The author has succeeded in presenting the facts in a clear and satisfactory manner, 
using simple language and copious illustration in the presentation of facts and prin- 
ciples, confining himself, however, to the physical aspect of the subject. In the Ap- 
pendix the operation of the principles in the spheres of life and mind is supplied by 
the essays of Professors Le Conte and Bain." — Ohio Farmer. 

" Prof. Stewart is one of the best known teachers in Owens College in Manchester. 

"The volume of The International Scientific Series now before us is an ex- 
cellent illustration of the true method of teaching, and will well compare with Prof. 
Tyndall's charming little book in the same series on ' Forms of Water," with illustra- 
tions enough to make clear, but not to conceal his thoughts, in a style simple and 
brief." — Christian Register, Boston. 

" The writer has wonderful ability to compress much information into a few words. 
It is a rich treat to read such a book as this, when there is so much beauty and force 
combined with such simplicity. — Eastern Press. 



VIII. 

Animal Locomotion; 

Or, WALKING, SWIMMING, AND FLYING. 

With a Dissertation on Aeronautics. 

By J. BELL PETTIGREW, M. D., F. R. S., F, R. S. E., 
F. R.C. P.E. 

I vol., i2mo Price, $1.75. 

" This work is more than a contribution to the stock of entertaining knowledge, 
though, if it only pleased, that would be sufficient excuse for its publication. But Dr. 
Pettigrew has given his time to these investigations with the ultimate purpose of solv- 
ing the difficult problem of Aeronautics. To this he devotes the last fifty pages of his 
book. Dr. Pettigrew is confident that man will yet conquer the domain of the air." — 
N. Y. Journal of Commerce. 

^ "Most persons claim to know how to walk, but few could explain the mechanical 
principles involved in this most ordinary transaction, and will be surprised that the 
movements of bipeds and quadrupeds, the darting and rushing motion of fish, and the 
erratic flight of the denizens of the air, are not only anologous, but can be reduced to 
similar formula. The work is profusely illustrated, and, without reference to the theory 
it is designed to expound, will be regarded as a valuable addition to natural history." 
'—Omaha Republic. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. ¥♦ 



Opinions of the Press on the "International Scientific Series:' 



IX. 

Responsibility in Mental Disease. 

By HENRY MAUDSLEY, M. D., 

Fellow of the Royal College of Physicians ; Professor of Medical Jurisprudence 
in University College, London. 

lvol.,i2mo. Cloth. .... Price, $1.50. 

"Having lectured in a medical college on Mental Disease, this book has been a 
feast to us. It handles a great subject in a masterly manner, and, in our judgment, 
the positions taken by the author are correct and well sustained.^ In his second chap- 
ter he has well marked out the border-line between sanity and insanity, speaks ot the 
prophets of the Old Testament, the epileptic nature of Mahomet's visions crime and 
insanity, epileptic insanity, etc. Here we can bear testimony to the truth of his re- 
marks from professional experience, having had probably more epileptic patients than 
any other physician of our day to treat." — Pastor and People. 

" The author is at home in his subject, and presents his views in an almost singu- 
larly clear and satisfactory manner. . . . The volume is a valuable contribution to one 
of the most difficult, and at the same time one of the most important subjects of inves- 
tigation at the present day."— N. V. Observer. 

" It is a work profound and searching, and abounds in wisdom." — Pittsburg Com- 
mercial. 

" Handles the important topic with masterly power, and its suggestions are prac- 
tical and of great value." — Providence Press. 

"Dr. Maudsley's book appears to us timely and valuable as bringing within the 
reach of every person the facts which, to the multitude, are often inaccessible." — 
Chicago Tribune. 

"Dr. Maudsley's treatise cannot but have an influence on the jurisprudence of the 
future with respect to the insane." — Buffalo Courier. 

"A compact presentation of those facts and principles which require to be taken 
in'-o account in estimating human responsibility." — Popular Science Monthly. 

" The International Scientific Series, whose merits have commanded such 
a prompt and extended recognition by the reading and thinking public, has its scope 
considerably enlarged by the publication of this, its latest volume. The treatise of 
Prof. Maudsley relates to a subject of peculiar interest, and which to every one has 
more or less importance. How far insanity, whether partial or entire, affects the re- 
sponsibility of the sufferer, is ably argued, the importance of the question warranting 
the length of the treatise, which the admirable style of the author renders of constant 
interest throughout." — Boston Post. 

11 The author has evidently devoted much study to his theme, which he discusses 
with commendable common-sense. His style is clear and his essay is decidedly inter- 
esting." — The Cultivator and Country Gentleman. 

" The style is clear and vigorous. In the chapter on Law and Insanity the author 
commends himself, by his acute criticisms and judicial deliverances, to the attention of 
lawyers." — The Christian Era. 

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y. 



A rich list of fruitful topics." 

Boston Commonwealth. 



HEALTH AND EDUCATION, 

By the Rev. CHARLES KINGSLEY, F. L. S., F. G. S., 

CANON OF WESTMINSTER. 

l2mo. Cloth Price, $1.75. 

" It is most refreshing to meet an earnest soul, and such, preeminently, is Charles 
Kingsley, and he has shown himself such in every thing he has written, from * Alton 
Locke ' and ' Village Sermons/ a quarter of a century since, to the present volume, which 
is no exception. Here are fifteen Essays and Lectures, excellent and interesting in 
different degrees, but all exhibiting the author's peculiar characteristics of thought 
and style, and some of them ^lending most valuable instruction with entertainment, 
as few living writers can.*' — Hartford Post. 

"That the title of this book is not expressive of its actual contents, is made mani- 
fest by a mere glance at its pages ; it is, in fact, a collection of Essays and Lectures, 
written and delivered upon various occasions by its distinguished author; as such it 
cannot be otherwise than readable, and no intelligent mind needs to be assured that 
Charles Kingsley is fascinating, whether he treats of Gothic Architecture, Natural 
History, or the Education of Women. The lecture on Thrift, which was intended for 
the women of England, may be read with profit and pleasure by the women of 
everywhere." — St. Louis Democrat. 

" The book contains exactly what every one needs to know, and in a form which 
every one can understand." — Boston Journal. 

" This volume no doubt contains his best thoughts on all the most important topics 
of the day." — Detroit Post. 

" Nothing could be better or more entertaining for the family library."— Zion's 
Herald. 

" For the style alone, and for the vivid pictures frequently presented, this latest 
production of Mr. Kingsley commends itself to readers. The topics treated are 
mostly practical, but the manner is always the manner of a master in composition. 
Whether discussing the abstract science of health, the subject of ventilation, the 
education of the different classes that form English society, natural history, geology, 
heroic aspiration, superstitious fears, or personal communication with Nature, we 
find the same freshness of treatment, and the same eloquence and affluence of language 
that distinguish the productions in other fields of this gifted author." — Boston Gazette. 

D. APPLETON & CO., Publishers, 

549 & 55 1 Broadway, N. Y. 



THE GREAT ICE AGE, 

AND ITS RELATIONS TO THE ANTIQUITY OF MAN. 

By JAMES GEIKIE, F. R. S. E. 

With Maps, Charts, and numerous Illustrations. 

I vol., thick l2mo. . . . Price, $2.50. 



OPINIONS OF THE PRESS. 

" Intelligent general readers, as well as students of geology, will find more infor- 
mation and reasonable speculation concerning the great glacial epoch of our globe in 
this votume than can be gathered from a score of other sources. The author writes 
not only for the benefit of his ' fellow-hammerers,' but also for non-specialists, and 
any one gifted with curiosity in respect to the natural history of the earth will be de- 
lighted with the clear statements and ample illustrations of Mr. Geikie's ' Great Ice 
Age.' " — Episcopal Register. 

" ■ The Great Ice Age ' is a work o( extraordinary interest and value. The subject 
is peculiarly attractive in the immensity of its scope, and exercises a fascination over the 
imagination so absorbing that it can scarcely find expression in words. It has all the 
charms of wonder-tales, and excites scientific and unscientific minds alike."— Boston 
Gazette. 

" Mr. Geikie has succeeded in writing one of the most charming volumes in the 
library of popularized science." — Utica Herald. 

" We cannot too heartily commend the style of this book, which is scientific and yet 
popular, and yet not so popular as to dispense with the necessity of the reader's putting 
his mind to work in order to follow out the author in his forcible yet lucid arguments. 
Nor can the attentive reader fail to leave the work with the same enthusiasm over the 
subject as is shown in every page by the talented author."— Portland Press. 

" Although Mr. Geikie's position in the scientific world is such as to indicate that 
he is a pretty safe teacher, some of his views are decidedly original, and he does not 
make a point of sticking to the beaten path." —Springffeld Union. 

"Prof. Geikie's book is one that may well engage thoughtful students other than 
geologists, bearing as it does on the absorbing question of the unwritten history of our 
race. The closing chapter of his work, in which, reviewing his analytical method, he 
constructs the story of the checkered past of the last 200,000 years, can scarcely fail to 
give food for thought even to the indifferent."— Buffalo Courier. 

"Every step in the process is traced with admirable perspicuity and fullness by 
Mr. Geikie."— London Saturday Review. 

" It offers to the student of geology by far the completest account of the period yet 
published, and is characterized throughout by refreshing vigor of diction and originality 
of thought."— Glasgow Herald. 

D. APPLETON & CO., Publishers, 

549 & 55 ! Broadway, N. Y. 



PRINCIPLES 



OF 



MENTAL PHYSIOLOGY, 

WITH 

Their Applications to the Training and Discipline of the Mind, and 
the Study of its Morbid Conditions, 

By WILLIAM CARPENTER, M. D., LL.D. 

I vol., i2mo. 737 pages. Price, $3.00* 

"Dr. Carpenter has won his reputation as a physiologist, largely 
from the clearness of his expositions, and the present work shows that 
his capacity in this respect is still vigorous. Its most scientific parts 
are attractive reading, and the extensive array of personal instances 
and incidents, which illustrate his positions, gives great fascination to 
the volume. 

" It is a hard book to lay down when once entered upon, and Dr. 
Carpenter may be congratulated upon having contributed so fresh a 
book upon such an important subject.' ' — Popular Science Monthly, 

" Is a profound and learned work, which goes to the very bottom of 
the problems of Life and Eternity." — Boston Commonwealth. 

"The work is probably the ablest exposition of the subject which 
has been given to the world, and goes far to establish a new system of 
mental philosophy upon a much broader and more substantial basis, 
than it has heretofore stood." — St. Louis Democrat. 

" The work is a revision and expansion of the author's well-known 
work bearing the same name, published over twenty years ago, and 
so popular as to reach half a dozen editions." — Cincinnati Gazette. 

D. APPLETON & CO., Publishers, 

549 & 551 Broadway, N. V. 



A 7i Interesting and Instructive Volume. 



FRENCH HOME LIFE. 

Reprinted from Blackwood. 
I vol., I2MO. Cloth. Price, $1.50. 



OPINIONS OF THE PRESS. 

New York Tribune. 
"The way in which their neighbors live is always an object of curi- 
osity with a large class of inquiring minds that can find no other vent 
for the divine energies of their nature. It is not often that the subject 
falls into the hands of persons with so much good sense and just per- 
ceptive powers, as the author of this volume. He professes to have 
resided in France for many years, and, in fact, to have found a second 
home in that country, so that he is entitled to speak with the freedom 
and authority of personal experience. At all events, he shows an equal 
familiarity with the domestic customs of England and of France, his 
comparisons are often piquant as well as informing, and if he lifts the 
roof from many a private me'nage in the capital, it is because he can dis- 
close nothing to disadvantage in the interior." 

Boston Journal. 
" The Appletons publish an interesting volume on * French Home 
Life,' reprinted from Blackwood 1 s Magazine. The author has lived 
among the French for twenty-five years or more, and has made a study 
of their character and ways of life. The book is fresh and entertaining 
in style, and conveys a good deal of information. ,, 

Episcopal Register. 
"The writer of this volume, an Englishman, has lived for a quarter 
of a century in France, amid ties and affections which have made that 
country his second home. He tells us, pleasantly and instructively, of 
French children, food, manners, language, furniture, dress, marriage, 
and servants, conveying much authentic information upon these inter- 
esting topics. The fact that this series of papers originally appeared in 
Blackwood' } s Magazine proves their high character." 

The Presbyterian. 
"The book is one of decided interest, full of every-day affairs, of 
home life, the life which is passed under a roof and at a fireside. The 
themes are Servants, Children, Furniture, Food, Manners, Dress, etc. 
The style is very pleasant, and the book one which throws much light 
on the real state of French society." 

D. APPLETON & CO., Publishers, 

549 <5r> 551 Broadway, New York. 



mgkt/ula* \ to the fat s iiteratmr* 



RELIGION AND SCIENCE. 



A Series o( Sunday lectures on the Relation o( Natural and Revealed 
Religion, or the [ruths revealed in Nature and Scripture. 

By JOSEPH LE CONTE, 
mnotssob wr qbologi am> kaxu&al msroai in ran ronvzasirs or gaufodua, 

12 ., $1.50. 

OPINIONS or 1111 rni:ss. 

" This work is chiefly remarkable as a conscientious effort to reconcile 

the revelations of Science with those oi Scripture, and will be very use- 
ful to teachers of the different Sunday -schools/' — Detrmt Uni 

"It will be seen, bv this rismmi o\ the topics, that Prof, l.e Contc 
grapples with some o( the gravest questions which agitate the thinking" 
world, lie treats of them all with dignity and fairness, and in a man- 
ner so clear, persuasive, and eloquent, as to engage the undivided at- 
tention of the reader. We commend the hook cordially to the regard 
of all who are interested in whatever pertains to the discussion of these 
grave questions, and especially to those who desire to examine closely 
the strong foundations on which the Christian faith is reared." — B<K 

11 A reverent student o( Nature and religion is the best-qualified man 
to instruct others in their harmony. The author at first intended his 
work for a Bible-class, but. as it grew under his hands, it seemed well to 
give it form in a neat volume. The lectures are from a decidedly re- 
ligious stand-point, and as such present a new method of treatment." 
— Pki 

•• This volume is made up of lectures delivered to his pupils, and is 
written with much clearness o\ thought and unusual clearness ol ex- 
pression, although the author's English is not always above reproach. 
It is partly a treatise on natural theology and partly a defense of the 
Bible against the assaults o\ modern science. In the latter aspect the 
author's method is an eminently wise one. lie accepts whatever sci- 
ence has proved, and he also accepts the divine origin of the Bible. 
Where the two seem to conflict he prefers to aw ait the reconciliation, 
which is inevitable if both are true, rather than to waste time and words 
in inventing ingenious ami doubtful theories to force them into seeming 
d. both a- a theologian and a man of science. Prof. 1 e Conte's 
- wre entitled to respectful attention, and there are few who will 
not recognize his book as a thoughtful and valuable contribution to the 
best religious literature of the day." — >•/</. 

D. \VV\ V. TON vt CO.. Publishers, 549 & 5SI Broadway. X. V. 



Eleventh Edition, Entirely Revised. 



Principles of Geology; 

OR, 

THE MODERN CHANGES OF THE EARTH 

AND 

ITS INHABITANTS CONSIDERED AS ILLUSTRA TIVE OF GEOLOCY- 
In 2 Vols. 8vo. Cloth. 
ILLUSTRATED WITH MAPS, PLATES, AND WOODCUTS. 
PRICE, $8.00. 



" 1 have followed the rule adopted in my first volume, of reprinting the Preface to 
the tenth edition, by which the reader will be directed to those numerous and impor- 
tant additions and corrections which I found necessary, in consequence of the progress 
of the science during the fifteen years which separated the ninth and tenth editions." — 
Extract from Preface. 

In this last edition of Principles of Geology, Sir Charles Lyell has set the seal 
of his matured experience and convictions upon a work which has for years held the 
position of a classic in the literature of science. Encyclopaedic in its scope, and ex- 
haustive in its treatment of every department of that study for which our language has 
no name exactly equivalent to the German Erdkunde, the Principles of Geology 
may be looked upon with pride, not only as a representative of English science, but as 
without a rival of its kind anywhere. Growing in fulness and accuracy with the growth 
of experience and observation in every region of the world, the work has incorporated 
with itself each established discovery, and has been modified by every hypothesis of 
value which has been brought to bear upon, or been cnvolved from, the most recent 
body of facts. Its successive editions thus stand as a series of landmarks, indicating 
the gradual expansion or rise of geological knowledge during a lifetime happily pro- 
longed over at least two average generations. In the impression now before us, the 
veteran geologist might be expected to have comparatively little to add by way of novel 
matter to the thoroughly revised and largely rewritten edition, the tenth in order, which 
he put forth scarcely more than three years ago, separated as that edition was by an 
interval of fifteen years from that immediately preceding it. There are, notwithstand- 
ing, sundry points of importance which call for notice as contributing to the facts com- 
prised within his general scope, as well as enhancing the unity and force of the argu- 
ment which runs through the length and breadth of his system. These editions have 
reference in the main to three large questions which may be said just now to engross 
among them the most lively and active interest among students of Nature. The first 
of these questions is that of volcanic action, as manifested especially in geysers, or as 
diversely affected by water. The second Is the latest phase assumed by the discussion 
upon the Darwinian theory. And the third is the existence and distribution of oceanic 
life at great depths, as determined by recent dredging operations. 

D. APPLETON & CO., Publishers, 

549 & 531 BROADWAY, NEW YOPK. 



NEW WORK BY MR. DARWIN. 



Now ready. I vol. Thick i2mo. With Illustrations. $3.50. 

The Expression of the Emotions 
in Man and Animals. 

By CHARLES DARWIN, F. R. S., Author of the " Origin of Species," etc., etc. 

"Whatever one thinks of Mr. Darwin's theory, it must be admitted that his great 
powers of observation are as conspicuous as ever in this inquiry. During a space ot 
more than thirty years, he has, with exemplary patience, been accumulating informa- 
tion from all available sources. The result of all this is undoubtedly the collection of a 
mass of minute and trustworthy information which must possess the highest value, 
whatever may be the conclusions ultimately deduced from it." — London Times. 

" It is almost needless to say that Mr. Darwin has brought to this work vast stores 
of erudition, accumulated treasures of careful observation, and all the devices of an 
acute and fertile ingenuity; for these are qualities which are conspicuous in all he 
writes. But it may be as well to add that the book is very attractive even to general 
readers. It is comparatively light and easy reading, full of amusing anecdote ; and the 
illustrations, whether due to the sun's rays or to the engraver's point, are excellent." — 
Guardian. 

" Those of our readers who know the charm of Darwin's former works, how he 
leads his readers on to his conclusions in the clearest and most attractive English, will 
experience more than their usual treat when they sit down to this book. Never was 
more truly realized the saying about men laboring and others entering into the fruit of 
their labors. The illustrations are excellent, and recourse has been had to photographs 
in rendering the more telling of the physiognomical expressions. Even the most an- 
tagonistic of anti-Darwinians will not hesitate to admit how much he has learned from 
a careful study of the work before us." — Science Gossip. 



RECENTLY PUBLISHED. 



A NEW EDITION OF 



Darwin's Origin of Species. 

FROM THE SIXTH AND LAST ENGLISH EDITION, 
Containing the Author's Latest Corrections and Additions^ 

From an entirely new set of stereotype plates. i2mo. Cloth. Price, $2.00. 

D. APPLETON & CO.. Publishers. 



JOURNAL .OF RESEARCHES 



NATURAL HISTORY AND GEOLOGY 

01" THE COUNTRIES VISITED 

DURING THE VOYAGE OF H. M. 8. BEAGLE BOUND 

THE WORLD, UNDER THE COMMAND OF 

CAPTAIN FITZROY, R. N. 

By CHARLES DARWIN, M.A., P. U.S., 

Author of "Origin of Species," etc., etc* 

One vol., l£3mo. 519 pages. IPrice, cloth, $2.00. 



44 This volume contains, in the form of a journal, a history of our voyage and a 
■ketch of those ohservations in Natural History and Geology which, I think, will pos- 
sess some interest for the general reader."— From the Author's Preface. 

" I have too deeply enjoyed the voyage not to recommend any naturalist, although 
he may not expect to be so fortunate in his companions as I have been, to take all 
chances, and to start on travels by land if possible, if otherwise, on a long voyage. He 
may feel assured he will meet with no difficulties or dangers, except in rare cases, 
nearly so bad as he beforehand anticipates."— Extract. 

" An intensely interesting work, written in a style that is a model of brevity and 
clearness."— Wisconsin State Journal. 

" Darwin was nearly five years on board the Beagle. A keen observer and a genu- 
ine philosopher, he has brought back to us a precious freight of facts and truths. 
The work has been some time before the public, and has won a high place among read- 
ers of every class. It is not so scientific as to be above the comprehension of intel- 
ligent readers who are not scientific. Some facts and species, new even to the scien- 
tific, are brought to light. Darwin's transparent, eloquent style richly illuminates 
his observations. The weightier matters to which we allude are interspersed among 
more familiar observations, such as would naturally be made by a traveller passing 
through new and wonderful scenes. It is an instructive and interesting book."— 
Northwestern Christian Advocate. 

JD. APPLETON & CO., 

549 & 551 Broadway, New York. 



An Important Work for Manufacturers, Chemists, and Students. 



A HAND-BOOK 



Chemical Technology. 

By Rudolph Wagner, Ph. D., 

PROFESSOR OF CHEMICAL TECHNOLOGY AT THE UNIVERSITY OF WURTZBURG. 

Translated and edited, from the eighth German edition, with extensive 

Additions, 

By Wm. Crookes, F. R. S. 

With 336 Illustrations. zvol.,%vo. 761 fages. Cloth, $5.00. 



The several editions of Professor Rudolph Wagner's " Handbuch det 

Chemischen Technologie " have succeeded each other so 

rapidly, that no apology is needed in offering 

a translation to the public. 

Under the head of Metallurgic Chemistry, the latest methods of preparing Iron, 
Cobalt, Nickel, Copper, Copper Salts, Lead and Tin and their Salts, Bismuth, Zinc, 
Zinc Salts, Cadmium, Antimony, Arsenic, Mercury, Platinum, Silver, Gold, Man- 
.ganates, Aluminum, and Magnesium, are described. The various applications of the 
Voltaic Current to Electro-Metallurgy follow under this division. The Preparation of 
Potash and Soda Salts, the Manufacture of Sulphuric Acid, and the Recovery of Sul- 
phur from Soda- Waste, of course occupy prominent places in the consideration of 
chemical manufactures. It is difficult to over-estimate the mercantile value of Mond's 
process, as well as the many new and important applications of Bisulphide of Carbon. 
The manufacture of Soap will be found to include much detail. The Technology of 
Glass, Stoneware, Limes and Mortars, will present much of interest to the Builder and 
Engineer. The Technology of Vegetable Fibres has been considered to include the 
preparation of Flax, Hemp, Cotton, as well as Paper-making ; while the applications 
of Vegetable Products will be found to include Sugar-boiling, Wine and Beer Brewing, 
the Distillation of Spirits, the Baking of Bread, the Preparation of Vinegar, the Preser- 
vation of Wood, etc. 

Dr. Wagner gives much information in reference to the production of Potash from 
Sugar-residues. The use of Baryta Salts is also fully described, as well as the prepa- 
ration of Sugar from Beet-roots. Tanning, the Preservation of Meat, Milk, etc., the 
Preparation of Phosphorus and Animal Charcoal, are considered as belonging to the 
Technology of Animal Products. The Preparation of the Materials for Dyeing has 
necessarily required much space ; while the final sections of the book have been de- 
voted to the Technology of Heating and Illumination. 

D. APPLETON & CO., Publishers. 



DESCRIPTIVE SOCIOLOGY. 



Mb. Herbert Spencer has been for several years engaged, with the aid of 
three educated gentlemen in his employ, in collecting and organizing the facts 
concerning all orders of human societies, which must constitute the data of a true 
Social Science. He tabulates these facts so as conveniently to admit of ex- 
tensive comparison, and gives the authorities separately. He divides the races 
of mankind into three great groups : the savage races, the existing civilizations, 
and the extinct civilizations, and to each he devotes a series of works. The 
first installment, 

THE SOCIOLOGICAL HISTORY OF ENGLAND, 

in seven continuous tables, folio, with seventy pages of verifying text, is now 
ready. This work will be a perfect Cyclopaedia of the facts of Social Science, 
independent of all theories, and will be invaluable to all interested in social 
problems. Price, five dollars. This great work is spoken of as follows : 

From the British Quarterly Review. 
41 No words are needed to indicate the immense labor here bestowed, or the great 
sociological benefit which such a mass of tabulated matter done under such competent 
direction will confer. The work will constitute an epoch in the science of comparative 
sociology." 

From the Saturday Review. 

44 The plan of the 4 Descriptive Sociology ' is new, and the task is one eminently fitted 
to be dealt with by Mr. Herbert Spencer's faculty of scientific organizing. His object is 
to examine the natural laws which govern the development of societies, as he has ex- 
amined in formei parts of his system those which govern the development of individual 
life. Now, it is obvious that the development of societies can be studied only in their 
history, and that general conclusions which shall hold good beyond the limits of particu- 
lar societies cannot be safely drawn except from a very wide range of facts. Mr. Spen- 
cer has therefore conceived the plan of making a preliminary collection, or perhaps we 
ihonld rather say abstract, of materials which when complete will be a classified epi- 
tome of unive. sal history." 

From the London Examiner. 

44 Of the treatment, in the main, we cannot speak too highly; and we must accept 
It as a wonderfully successful first attempt to furnish the student of social science with 
data standing toward his conclusions in a relation like that in which accounts o* the 
structures and functions of different types of animals stand to the conclusion? of the 
biologist." 



THE NEW AND CHEAPER EDITION OF 

FIGUIER'S 

POPULAR SCIENTIFIC WORKS, 

Containing all the Original Illustrations, With the Text 
thoroughly revised and corrected. 

Price, $3.50 each. 



The World before the Deluge. 

The Geological Portion carefully revised, and much new matter added, by H. W. 
Bristow, F. R. S., of the Geological Survey of Great Britain, Hon. Fellow of 
King's College, London. With 233 Illustrations. 1 vol., 8vo. Price, $3.50. 
"A book worth a thousand gilt Christmas volumes, and one most suitable as a gift 
to an intellectual and earnestly-inquiring student." — Athenceum. 

The Ocean World. 

Being a Description of the Sea and its Living Inhabitants. Revised and corrected 
by Professor E. Percival Wright, M. D. With 427 Illustrations. 1 vol., 8vo. 
Price, $3.50. 

The Insect World. 

A Popular Account of the Orders of Insects. Revised and corrected by P. Martin 
Duncan, M. D., F. R. S., Professor of Geology in King's College, London. 
With 576 Illustrations. 1 vol., 8vo. Price, $3.50. 
" Remarkable at once for the beauty and variety of its illustrations. The book is an 
excellent one, and admirably got up." — Educational Times. 

The Vegetable World. 

A History of Plants, with their Botanical Descriptions and Peculiar Properties, 
and a Glossary of Botanical Terms. New edition, revised and corrected by an 
eminent Botanist. With 470 Illustrations. 1 vol., 8vo. Price, $3.50. 
" Throughout the book we have evidence of careful editorship in various little altera- 
tions which render it more suitable to the British Botanist, and in additions which 

bring it up to the present state of botanical science The present edition of 

' The Vegetable World ' is, so far as botanical value is concerned, the best which has 
appeared, not excepting the original French issue." — The Garden. 

Reptiles and Birds. 

Revised and corrected by Captain Parker Gillmore. With 307 Illustrations. 
1 vol., 8vo. Price, $3.50. 

Either of the above sent free by mail to any address on receipt of the price. 

D. APPLETON & CO., Publishers. 



The Colored Plates illustrating this edition of the work, requiring great care 
in printing, were executed in London. 



SPECTRUM ANALYSIS, 

In its Application to Terrestrial Substances, and the Physical 
Constitution of the Heavenly Bodies, 

Familiarly explained, by Dr. H. Schellen, Director der Kealschule 
I. 0. Cologne. Translated from the second enlarged and revised 
German edition, by Jane and Caroline Lassell. Edited, with 
Notes, by William Huggins, LL. D. With numerous Woodcuts, 
Colored Plates, and Portraits ; also, Angstrom's and Kirchhoff's 
Maps. 455 pages, 8vo, cloth. Price, $6.00. 



From, the Chemical News. 

" This admirable work does credit to, or should we say is worthy of the 
author, the translators, and the editor. The first part treats on the artificial 
sources of high degrees of heat and light ; the second on Spectrum Analysis 
in its application to the heavenly bodies. We must approve the method fol- 
lowed in the translation, and by the editor. In many translations the views 
of the author are suppressed, in order that the views of the translator or 
editor may be expounded; but here Dr. Huggins, however leniently such a 
fault might have been looked upon with him, has permitted the author's 
views to remain intact, clearly stating his own and wherein lies the differ- 
ence. 1 ' 

From the Chicago Tost. 

" The object of this volume is to introduce the general reader into a new 
realm of science, and acquaint him with the particulars and the results of 
the most brilliant discovery of the present century. Whoever has an appre- 
ciative sense of the beauties and wonders of Nature, illuminated by science, 
will find this volume a rich mine of enjoyment which he will do wisely to 
explore." 

From the Philadelphia Age. 

" The contents are formidable in appearance, but the average reader will 
find its exposition easily intelligible. To many the revelations of this book, 
so marvellously minute, and yet so unerringly accurate, will be as wonder- 
ful as the stories of the 4 Arabian Nights* 1 " 

From the Boston Globe, 

" Certainly, as regards mere knowledge, the Spectrum Analysis has let 
us into many secrets of the physical universe, which Newton and La Place 
would have declared impossible for man's intellect to attain. The science 
is still in its infancy, but it is prosecuted by some of the ablest, most pa- 
tient, and most enthusiastic observers, and some of the keenest thinkers, 
at present existing on our little, insignificant physical globe." 

D. APPLETON & CO., Publishers, 

549 & 551 BROADWAY, N. T. 



THE WORKS OF 

Prof, JOHN TYNDALL, ILD., P.R.S. 



V. 
HOURS OF EXERCISE IN THE ALPS. 

One vol., i2mo. With Illustrations. Cloth, $2.00. 

" The present volume is for the most part a record of bodily action, written partly to 
preserve to myself the memory of strong and joyous hours, and partly for the pleasure of 
those who find exhilaration in descriptions associated with mountain-life." — From Author's 
Preface. 

VI. 
FARADAY AS A DISCOVERER. 

One vol., i2mo. Cloth, $1.00. 

'* It has been thought desirable to give you and the world some image of Michael 

Faraday as a scientific investigator and discoverer. I have 

returned from my task with such results as I could gather, and also with the wish that 
these results were more worthy than they are of the greatness of my theme." — The 
Author. 

VII. 

FORMS OF WATER, IN CLOUDS, RAIN, RIVERS, ICE, 
AND GLACIERS. 

This is the first volume of the International Scientific Series, and is a valu- 
able and interesting work. One vol., i2mo. Cloth, $1.50. 

VIII. 

CONTRIBUTIONS TO MOLECULAR PHYSICS IN THE 
DOMAIN OF RADIANT HEAT. 

A Series of Memoirs published in the " Philosophical Transactions " and 
" Philosophical Magazine." With Additions. 

D. APPLETON & CO., Publishers, 

549 & 551 Broadway, N. Y. 



THE WORKS OF 

Prof. JOHN TYNDALL, LL.D., F.R.S. 



L 
HEAT AS A MODE OF MOTION. 

One vol., l2mo. Cloth, $2.00. 

" My aim has been to rise to the level of these questions from a basis so elementary thai 
& person possessing any imaginative faculty and power of concentration might accoin* 
pany me."— From Author's Preface. 

II. 
ON SOUND. 

A Course of Eight Lectures delivered at the Royal Institution of Great 
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